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Polynomials-and-rational-expressions/133259: I need help trying to solve this. 6x-18/2x^2-5x+3* 4x^2+4x+1/ 6x+3
1 solutions

Answer 97470 by jim_thompson5910(28595) About Me  on 2008-03-22 21:30:44 (Show Source):
You can put this solution on YOUR website!
%28%286x-18%29%2F%282x%5E2-5x%2B3%29%29%28%284x%5E2%2B4x%2B1%29%2F%286x%2B3%29%29 Start with the given expression

Factor 6x-18 to get 6%28x-3%29 and factor 6 to get %282%2A3%29

Factor 2x%5E2-5x%2B3 to get %282x-3%29%28x-1%29

Factor 4x%5E2%2B4x%2B1 to get %282x%2B1%29%282x%2B1%29

Factor 6x%2B3 to get 3%282x%2B1%29


%282%2A3%29%28x-3%29%282x%2B1%29%282x%2B1%29%2F%282x-3%29%28x-1%293%282x%2B1%29 Combine the fractions


Cancel like terms


%282%28x-3%29%282x%2B1%29%29%2F%28%282x-3%29%28x-1%29%29 Simplify



--------------------------------------------------
Answer:

So %28%286x-18%29%2F%282x%5E2-5x%2B3%29%29%28%284x%5E2%2B4x%2B1%29%2F%286x%2B3%29%29 simplifies to %282%28x-3%29%282x%2B1%29%29%2F%28%282x-3%29%28x-1%29%29. In other words


Exponential-and-logarithmic-functions/133258: Use logs on both sides of the equation
9^28 - 9^27 / 8 = 3^x to find the unknown
Please show all steps
The 8 is dividing (9^28 - 9^27)
1 solutions

Answer 97468 by jim_thompson5910(28595) About Me  on 2008-03-22 21:23:41 (Show Source):
You can put this solution on YOUR website!
%289%5E28+-+9%5E27%29+%2F+8+=+3%5Ex+ Start with the given equation


%289%5E%2827%2B1%29+-+9%5E27%29+%2F+8+=+3%5Ex+ Rewrite 9%5E28 into 9%5E%2827%2B1%29



%289%5E27%2A9%5E1-+9%5E27%29+%2F+8+=+3%5Ex+ Break up 9%5E%2827%2B1%29 into 9%5E27%2A9%5E1 through the identity x%5E%28y%2Bz%29=x%5Ey%2Ax%5Ez


%289%5E27%289%5E1-+1%29%29+%2F+8+=+3%5Ex+ Factor out the GCF 9%5E27


%289%5E27%289-+1%29%29+%2F+8+=+3%5Ex+ Evaluate 9%5E1 to get 9


%289%5E27%288%29%29+%2F+8+=+3%5Ex+ Subtract


%289%5E27cross%288%29%29+%2F+cross%288%29+=+3%5Ex+ Cancel like terms


9%5E27+=+3%5Ex+ Simplify


%283%5E2%29%5E27+=+3%5Ex+ Rewrite 9 as 3%5E2


3%5E%282%2A27%29+=+3%5Ex+ Multiply the exponents. Remember, %28x%5Ey%29%5Ez=x%5E%28y%2Az%29


3%5E54+=+3%5Ex+ Multiply


Since the bases are equal, the exponents are equal. So this means that x=54


Inequalities/133236: 12x + 5 ≤ 30 -2x
Help me please??!!
1 solutions

Answer 97430 by jim_thompson5910(28595) About Me  on 2008-03-22 19:02:11 (Show Source):
You can put this solution on YOUR website!

12x%2B5%3C=30-2x Start with the given inequality



12x%3C=30-2x-5Subtract 5 from both sides


12x%2B2x%3C=30-5 Add 2x to both sides


14x%3C=30-5 Combine like terms on the left side


14x%3C=25 Combine like terms on the right side


x%3C=%2825%29%2F%2814%29 Divide both sides by 14 to isolate x




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Answer:
So our answer is x%3C=25%2F14 (which is approximately x%3C=1.78571 in decimal form)


Radicals/133228: Radical Expressions
simplify.
I am trying to help my daughter with her homework and I am at a loss. I have never seen problems like these, and surely am at a loss as where to start with them.
\/810+\/240-\/250
1 solutions

Answer 97427 by jim_thompson5910(28595) About Me  on 2008-03-22 16:58:46 (Show Source):
You can put this solution on YOUR website!
sqrt%28810%29%2Bsqrt%28240%29-sqrt%28250%29 Start with the given expression


9%2Asqrt%2810%29%2Bsqrt%28240%29-sqrt%28250%29 Simplify sqrt%28810%29 to get 9%2Asqrt%2810%29. Note: If you need help with simplifying square roots, check out this solver.


9%2Asqrt%2810%29%2B4%2Asqrt%2815%29-sqrt%28250%29 Simplify sqrt%28240%29 to get 4%2Asqrt%2815%29.


9%2Asqrt%2810%29%2B4%2Asqrt%2815%29-5%2Asqrt%2810%29 Simplify sqrt%28250%29 to get 5%2Asqrt%2810%29.


4%2Asqrt%2810%29%2B4%2Asqrt%2815%29 Combine like terms




-----------------------------------------

Answer:

So sqrt%28810%29%2Bsqrt%28240%29-sqrt%28250%29 simplifies to 4%2Asqrt%2810%29%2B4%2Asqrt%2815%29. In other words, sqrt%28810%29%2Bsqrt%28240%29-sqrt%28250%29=4%2Asqrt%2810%29%2B4%2Asqrt%2815%29


Linear-equations/133226: Please I am in dire need of this answer. it's urgent please.
Suppose a car rental company charges $150 for the first day and $100 for each additional or partial day. Let S(x) represent the cost of renting a car for x days. Find the value of S(5.5).
Happy easter.

1 solutions

Answer 97425 by jim_thompson5910(28595) About Me  on 2008-03-22 16:06:12 (Show Source):
You can put this solution on YOUR website!
Since the person has to pay $150 no matter what, this is the fixed cost. Also, since the cost for each day is $100, this is the variable cost. So the equation would follow the form


S(x)=Variable Cost * x + Fixed Cost


So in this case the equation is

S%28x%29=100x%2B150


S%285.5%29=100%285.5%29%2B150 Now plug in x=5.5 to evaluate S(5.5)


S%285.5%29=100%286%29%2B150 Round 5.5 to 6 (remember, it's $100 per day or partial day)

S%285.5%29=600%2B150 Multiply


S%285.5%29=750 Add


So this means that when x=5.5 the cost is $750


Graphs/133213: Find the equation of the line through the given pair of points in standard form using only integers?
(-4,-1) and (5,8)
1 solutions

Answer 97418 by jim_thompson5910(28595) About Me  on 2008-03-22 14:57:13 (Show Source):
You can put this solution on YOUR website!
First lets find the slope through the points (-4,-1) and (5,8)

m=%28y%5B2%5D-y%5B1%5D%29%2F%28x%5B2%5D-x%5B1%5D%29 Start with the slope formula (note: is the first point (-4,-1) and is the second point (5,8))

m=%288--1%29%2F%285--4%29 Plug in y%5B2%5D=8,y%5B1%5D=-1,x%5B2%5D=5,x%5B1%5D=-4 (these are the coordinates of given points)

m=+9%2F9 Subtract the terms in the numerator 8--1 to get 9. Subtract the terms in the denominator 5--4 to get 9


m=1 Reduce

So the slope is
m=1

------------------------------------------------


Now let's use the point-slope formula to find the equation of the line:



------Point-Slope Formula------
y-y%5B1%5D=m%28x-x%5B1%5D%29 where m is the slope, and is one of the given points

So lets use the Point-Slope Formula to find the equation of the line

y--1=%281%29%28x--4%29 Plug in m=1, x%5B1%5D=-4, and y%5B1%5D=-1 (these values are given)


y%2B1=%281%29%28x--4%29 Rewrite y--1 as y%2B1


y%2B1=%281%29%28x%2B4%29 Rewrite x--4 as x%2B4


y%2B1=x%2B%281%29%284%29 Distribute 1

y%2B1=x%2B4 Multiply 1 and 4 to get 4

y=x%2B4-1 Subtract 1 from both sides to isolate y

y=x%2B3 Combine like terms 4 and -1 to get 3
------------------------------------------------------------------------------------------------------------
Answer:


So the equation of the line which goes through the points (-4,-1) and (5,8) is:y=x%2B3

The equation is now in y=mx%2Bb form (which is slope-intercept form) where the slope is m=1 and the y-intercept is b=3

Notice if we graph the equation y=x%2B3 and plot the points (-4,-1) and (5,8), we get this: (note: if you need help with graphing, check out this solver)

Graph of y=x%2B3 through the points (-4,-1) and (5,8)

Notice how the two points lie on the line. This graphically verifies our answer.


Points-lines-and-rays/133221: Write the equation of the line perpendicular to y=2x-8 that passes through the point (4,0).
1 solutions

Answer 97417 by jim_thompson5910(28595) About Me  on 2008-03-22 14:54:12 (Show Source):
You can put this solution on YOUR website!
Solved by pluggable solver: Finding the Equation of a Line Parallel or Perpendicular to a Given Line


Remember, any two perpendicular lines are negative reciprocals of each other. So if you're given the slope of 2, you can find the perpendicular slope by this formula:

m%5Bp%5D=-1%2Fm where m%5Bp%5D is the perpendicular slope


m%5Bp%5D=-1%2F%282%2F1%29 So plug in the given slope to find the perpendicular slope



m%5Bp%5D=%28-1%2F1%29%281%2F2%29 When you divide fractions, you multiply the first fraction (which is really 1%2F1) by the reciprocal of the second



m%5Bp%5D=-1%2F2 Multiply the fractions.


So the perpendicular slope is -1%2F2



So now we know the slope of the unknown line is -1%2F2 (its the negative reciprocal of 2 from the line y=2%2Ax-8). Also since the unknown line goes through (4,0), we can find the equation by plugging in this info into the point-slope formula

Point-Slope Formula:

y-y%5B1%5D=m%28x-x%5B1%5D%29 where m is the slope and (x%5B1%5D,y%5B1%5D) is the given point



y-0=%28-1%2F2%29%2A%28x-4%29 Plug in m=-1%2F2, x%5B1%5D=4, and y%5B1%5D=0



y-0=%28-1%2F2%29%2Ax%2B%281%2F2%29%284%29 Distribute -1%2F2



y-0=%28-1%2F2%29%2Ax%2B4%2F2 Multiply



y=%28-1%2F2%29%2Ax%2B4%2F2%2B0Add 0 to both sides to isolate y

y=%28-1%2F2%29%2Ax%2B4%2F2%2B0%2F2 Make into equivalent fractions with equal denominators



y=%28-1%2F2%29%2Ax%2B4%2F2 Combine the fractions



y=%28-1%2F2%29%2Ax%2B2 Reduce any fractions

So the equation of the line that is perpendicular to y=2%2Ax-8 and goes through (4,0) is y=%28-1%2F2%29%2Ax%2B2


So here are the graphs of the equations y=2%2Ax-8 and y=%28-1%2F2%29%2Ax%2B2




graph of the given equation y=2%2Ax-8 (red) and graph of the line y=%28-1%2F2%29%2Ax%2B2(green) that is perpendicular to the given graph and goes through (4,0)




Graphs/133211: Find the distance between the points, and find the midpoint of the line segment joining them? (9,8) and (2,1)

1 solutions

Answer 97409 by jim_thompson5910(28595) About Me  on 2008-03-22 14:13:43 (Show Source):
You can put this solution on YOUR website!
First let's find the distance


Start with the given distance formula
d=sqrt%28%28x%5B1%5D-x%5B2%5D%29%5E2%2B%28y%5B1%5D-y%5B2%5D%29%5E2%29 where is the first point and is the second point

d=sqrt%28%289-2%29%5E2%2B%288-1%29%5E2%29 Plug in x%5B1%5D=9, x%5B2%5D=2, y%5B1%5D=8, y%5B2%5D=1

d=sqrt%28%287%29%5E2%2B%287%29%5E2%29 Evaluate 9-2 to get 7. Evaluate 8-1 to get 7.

d=sqrt%2849%2B49%29 Square each value

d=sqrt%2898%29 Add

d=7%2Asqrt%282%29 Simplify the square root (note: If you need help with simplifying the square root, check out this solver)


So the distance approximates to

d=9.89949493661167

which rounds to
9.89949

So the distance between (9,8) and (2,1) is approximately 9.89949 units







Now let's find the midpoint


In order to find the midpoint between the points (9,8) and (2,1), we need to average each corresponding coordinate. In other words, we need to add up the corresponding coordinates and divide the sum by 2.


So lets find the averages between the two points



To find , average the x-coordinates between the two points
x%5Bmid%5D=%289%2B2%29%2F2=%2811%29%2F2=5.5


So the x-coordinate of the midpoint is 5.5 (i.e. x=5.5)
-----------------------------------------------------------------------------------------------------------------


To find , average the y-coordinates between the two points
y%5Bmid%5D=%288%2B1%29%2F2=%289%29%2F2=4.5


So the y-coordinate of the midpoint is 4.5 (i.e. y=4.5)
-----------------------------------------------------------------------------------------------------------------
Answer:
Since the coordinates of the midpoint are x=5.5, y=4.5, this means the midpoint is (5.5,4.5)

Check:
Here is a graph to visually see the answer
Graph of the line segment with the endpoints (9,8) and (2,1) with the midpoint (5.5,4.5)



We could visually verify our answer if we simply draw right triangles from each point like this:


Here we can see that the two triangles are congruent (they both have a right angle and equal leg lengths), so our answer is verified.


Linear-equations/133205: This question is from textbook algebra math 009

how are these resolved
7y+4=-3,
5/2x-1=x+1/4

3(w+3)=2w+3
______
4
1 solutions

Answer 97406 by jim_thompson5910(28595) About Me  on 2008-03-22 13:03:36 (Show Source):
You can put this solution on YOUR website!
# 1



7y%2B4=-3 Start with the given equation



7y=-3-4Subtract 4 from both sides


7y=-7 Combine like terms on the right side


y=%28-7%29%2F%287%29 Divide both sides by 7 to isolate y



y=-1 Divide

--------------------------------------------------------------
Answer:
So our answer is y=-1









# 2



%285%2F2%29x-1=x%2B1%2F4 Start with the given equation



%284%29%28%285%2Fcross%282%29%29x-1%29=%284%29%28x%2B1%2Fcross%284%29%29 Multiply both sides by the LCM of 4. This will eliminate the fractions (note: if you need help with finding the LCM, check out this solver)



10x-4=4x%2B1 Distribute and multiply the LCM to each side



10x=4x%2B1%2B4Add 4 to both sides


10x-4x=1%2B4 Subtract 4x from both sides


6x=1%2B4 Combine like terms on the left side


6x=5 Combine like terms on the right side


x=%285%29%2F%286%29 Divide both sides by 6 to isolate x




--------------------------------------------------------------
Answer:
So our answer is x=5%2F6 (which is approximately x=0.83333 in decimal form)






# 3




%283%28w%2B3%29%29%2F4=2w%2B3 Start with the given equation



%284%29%28%283%28w%2B3%29%29%2Fcross%284%29%29=%284%29%282w%2B3%29 Multiply both sides by the LCM of 4. This will eliminate the fractions (note: if you need help with finding the LCM, check out this solver)



3%28w%2B3%29=8w%2B12 Distribute and multiply the LCM to each side



3w%2B9=8w%2B12 Distribute again


3w=8w%2B12-9Subtract 9 from both sides


3w-8w=12-9 Subtract 8w from both sides


-5w=12-9 Combine like terms on the left side


-5w=3 Combine like terms on the right side


w=%283%29%2F%28-5%29 Divide both sides by -5 to isolate w



w=-3%2F5 Reduce

--------------------------------------------------------------
Answer:
So our answer is w=-3%2F5 (which is approximately w=-0.6 in decimal form)



Age_Word_Problems/133204: rema is older than ken. the difference of their ages is 12 and the sum of their ages is 50. find the age of each
1 solutions

Answer 97405 by jim_thompson5910(28595) About Me  on 2008-03-22 12:49:38 (Show Source):
You can put this solution on YOUR website!


If "the difference of their ages is 12", then the first equation is x-y=12. Also, if "the sum of their ages is 50", then the second equation is x%2By=50.



So let's solve this system by using substitution







Start with the given system of equations:

system%28x-y=12%2Cx%2By=50%29



Now in order to solve this system by using substitution, we need to solve (or isolate) one variable. I'm going to solve for y.




So let's isolate y in the first equation

x-y=12 Start with the first equation


-y=12-x Subtract x from both sides


-y=-x%2B12 Rearrange the equation


y=%28-x%2B12%29%2F%28-1%29 Divide both sides by -1


y=%28%28-1%29%2F%28-1%29%29x%2B%2812%29%2F%28-1%29 Break up the fraction


y=x-12 Reduce



---------------------

Since y=x-12, we can now replace each y in the second equation with x-12 to solve for x



x%2Bhighlight%28%28x-12%29%29=50 Plug in y=x-12 into the first equation. In other words, replace each y with x-12. Notice we've eliminated the y variables. So we now have a simple equation with one unknown.



2x-12=50 Combine like terms on the left side


2x=50%2B12Add 12 to both sides


2x=62 Combine like terms on the right side


x=%2862%29%2F%282%29 Divide both sides by 2 to isolate x



x=31 Divide





-----------------First Answer------------------------------


So the first part of our answer is: x=31









Since we know that x=31 we can plug it into the equation y=x-12 (remember we previously solved for y in the first equation).



y=x-12 Start with the equation where y was previously isolated.


y=%2831%29-12 Plug in x=31


y=31-12 Multiply


y=19 Combine like terms



-----------------Second Answer------------------------------


So the second part of our answer is: y=19









-----------------Summary------------------------------

So our answers are:

x=31 and y=19


So the two ages are 31 and 19


Linear-equations/133203: This question is from textbook algebra math 009
How do I resolve this equation:
7n+5=10n-10
1 solutions

Answer 97402 by jim_thompson5910(28595) About Me  on 2008-03-22 12:18:11 (Show Source):
You can put this solution on YOUR website!

7n%2B5=10n-10 Start with the given equation



7n=10n-10-5Subtract 5 from both sides


7n-10n=-10-5 Subtract 10n from both sides


-3n=-10-5 Combine like terms on the left side


-3n=-15 Combine like terms on the right side


n=%28-15%29%2F%28-3%29 Divide both sides by -3 to isolate n



n=5 Divide

--------------------------------------------------------------
Answer:
So our answer is n=5



Polynomials-and-rational-expressions/133100: Use rational exponents to simplify.
root ( 3, x^6 )

1 solutions

Answer 97396 by jim_thompson5910(28595) About Me  on 2008-03-22 11:43:16 (Show Source):
You can put this solution on YOUR website!
Start with the given expression




Convert the expression from radical notation to exponent notation. Remember




Now multiply the exponents



Reduce





So simplifies to . In other words, where x is positive.


Polynomials-and-rational-expressions/133186: Use rational exponents to simplify.
root (3,x^6)
1 solutions

Answer 97395 by jim_thompson5910(28595) About Me  on 2008-03-22 11:42:34 (Show Source):
You can put this solution on YOUR website!
Start with the given expression




Convert the expression from radical notation to exponent notation. Remember




Now multiply the exponents



Reduce





So simplifies to . In other words, where x is positive.


Quadratic_Equations/133182: Solve.
x^2 + 6x -4 = 0
Here's what I think is the answer. Can someone tell me if I'm on the right track?
(-6 + sqrt (52)/2) (-6 - sqrt ( 52 )/2)
1 solutions

Answer 97393 by jim_thompson5910(28595) About Me  on 2008-03-22 11:37:26 (Show Source):
You can put this solution on YOUR website!
Let's use the quadratic formula to solve for x:


Starting with the general quadratic

ax%5E2%2Bbx%2Bc=0

the general solution using the quadratic equation is:

x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29



So lets solve x%5E2%2B6%2Ax-4=0 ( notice a=1, b=6, and c=-4)




x+=+%28-6+%2B-+sqrt%28+%286%29%5E2-4%2A1%2A-4+%29%29%2F%282%2A1%29 Plug in a=1, b=6, and c=-4



x+=+%28-6+%2B-+sqrt%28+36-4%2A1%2A-4+%29%29%2F%282%2A1%29 Square 6 to get 36



x+=+%28-6+%2B-+sqrt%28+36%2B16+%29%29%2F%282%2A1%29 Multiply -4%2A-4%2A1 to get 16



x+=+%28-6+%2B-+sqrt%28+52+%29%29%2F%282%2A1%29 Combine like terms in the radicand (everything under the square root)



x+=+%28-6+%2B-+2%2Asqrt%2813%29%29%2F%282%2A1%29 Simplify the square root (note: If you need help with simplifying the square root, check out this solver)



x+=+%28-6+%2B-+2%2Asqrt%2813%29%29%2F2 Multiply 2 and 1 to get 2

So now the expression breaks down into two parts

x+=+%28-6+%2B+2%2Asqrt%2813%29%29%2F2 or x+=+%28-6+-+2%2Asqrt%2813%29%29%2F2


Now break up the fraction


x=-6%2F2%2B2%2Asqrt%2813%29%2F2 or x=-6%2F2-2%2Asqrt%2813%29%2F2


Simplify


x=-3%2Bsqrt%2813%29 or x=-3-sqrt%2813%29


-------------------------------------------

Answer:



So the exact solutions are


x=-3%2Bsqrt%2813%29 or x=-3-sqrt%2813%29


So you are on the right track, but could simplify the answer.


Coordinate-system/133167: x+5y=10
1 solutions

Answer 97378 by jim_thompson5910(28595) About Me  on 2008-03-22 00:19:53 (Show Source):
You can put this solution on YOUR website!
Do you want to solve for y?




x%2B5y=10 Start with the given equation


5y=10-x Subtract +x from both sides


5y=-x%2B10 Rearrange the equation


y=%28-x%2B10%29%2F%285%29 Divide both sides by 5


y=%28-1%2F5%29x%2B%2810%29%2F%285%29 Break up the fraction


y=%28-1%2F5%29x%2B2 Reduce



So the equation is now in slope-intercept form (y=mx%2Bb) where the slope is m=-1%2F5 and the y-intercept is b=2


Polynomials-and-rational-expressions/133168: How do you factor the following problems step by step?
1. 9-x^2
2. 4x^2+81-36x
3. 4y^2+16y+16
4. x^-25/x+5
1 solutions

Answer 97376 by jim_thompson5910(28595) About Me  on 2008-03-22 00:14:00 (Show Source):
You can put this solution on YOUR website!
I'll do the first two to get you started


# 1

9-x%5E2 Start with the given expression

%283%29%5E2-x%5E2 Rewrite 9 as %283%29%5E2

%283%29%5E2-%28x%29%5E2 Rewrite x%5E2 as %28x%29%5E2


Now use the difference of squares. Remember, the difference of squares formula is A%5E2-B%5E2=%28A%2BB%29%28A-B%29 where in this case A=3 and B=x

9-x%5E2=%283%2Bx%29%283-x%29 Plug in A=3 and B=x



-------------------------------------------------

Answer:

So the expression

9-x%5E2

factors to

%283%2Bx%29%283-x%29

Notice that if you foil the factored expression, you get the original expression. This verifies our answer.





4x%5E2%2B81-36x Start with the given expression


4x%5E2-36x%2B81 Rearrange the terms




Looking at 4x%5E2-36x%2B81 we can see that the first term is 4x%5E2 and the last term is 81 where the coefficients are 4 and 81 respectively.

Now multiply the first coefficient 4 and the last coefficient 81 to get 324. Now what two numbers multiply to 324 and add to the middle coefficient -36? Let's list all of the factors of 324:



Factors of 324:
1,2,3,4,6,9,12,18,27,36,54,81,108,162

-1,-2,-3,-4,-6,-9,-12,-18,-27,-36,-54,-81,-108,-162 ...List the negative factors as well. This will allow us to find all possible combinations

These factors pair up and multiply to 324
1*324
2*162
3*108
4*81
6*54
9*36
12*27
18*18
(-1)*(-324)
(-2)*(-162)
(-3)*(-108)
(-4)*(-81)
(-6)*(-54)
(-9)*(-36)
(-12)*(-27)
(-18)*(-18)

note: remember two negative numbers multiplied together make a positive number


Now which of these pairs add to -36? Lets make a table of all of the pairs of factors we multiplied and see which two numbers add to -36

First NumberSecond NumberSum
13241+324=325
21622+162=164
31083+108=111
4814+81=85
6546+54=60
9369+36=45
122712+27=39
181818+18=36
-1-324-1+(-324)=-325
-2-162-2+(-162)=-164
-3-108-3+(-108)=-111
-4-81-4+(-81)=-85
-6-54-6+(-54)=-60
-9-36-9+(-36)=-45
-12-27-12+(-27)=-39
-18-18-18+(-18)=-36



From this list we can see that -18 and -18 add up to -36 and multiply to 324


Now looking at the expression 4x%5E2-36x%2B81, replace -36x with -18x%2B-18x (notice -18x%2B-18x adds up to -36x. So it is equivalent to -36x)

4x%5E2%2Bhighlight%28-18x%2B-18x%29%2B81


Now let's factor 4x%5E2-18x-18x%2B81 by grouping:


%284x%5E2-18x%29%2B%28-18x%2B81%29 Group like terms


2x%282x-9%29-9%282x-9%29 Factor out the GCF of 2x out of the first group. Factor out the GCF of -9 out of the second group


%282x-9%29%282x-9%29 Since we have a common term of 2x-9, we can combine like terms

So 4x%5E2-18x-18x%2B81 factors to %282x-9%29%282x-9%29


So this also means that 4x%5E2-36x%2B81 factors to %282x-9%29%282x-9%29 (since 4x%5E2-36x%2B81 is equivalent to 4x%5E2-18x-18x%2B81)


note: %282x-9%29%282x-9%29 is equivalent to %282x-9%29%5E2 since the term 2x-9 occurs twice. So 4x%5E2-36x%2B81 also factors to %282x-9%29%5E2



------------------------------------------------------------



Answer:
So 4x%5E2-36x%2B81 factors to %282x-9%29%5E2


Linear-equations/133147: Solve the system of equations using the addition (elimination) method.
If the answer is a unique solution, present it as an ordered pair: (x, y). If not, specify whether the answer is “no solution” or “infinitely many solutions.”
-7x + y = 8
2x – y = 2

1 solutions

Answer 97342 by jim_thompson5910(28595) About Me  on 2008-03-21 18:00:35 (Show Source):
You can put this solution on YOUR website!


Start with the given system of equations:

system%28-7x%2By=8%2C2x-y=2%29



Now in order to solve this system by using elimination/addition, we need to solve (or isolate) one variable. I'm going to solve for y.





In order to solve for one variable, we must eliminate the other variable. So if we wanted to solve for y, we would have to eliminate x (or vice versa).


So lets eliminate x. In order to do that, we need to have both x coefficients that are equal in magnitude but have opposite signs (for instance 2 and -2 are equal in magnitude but have opposite signs). This way they will add to zero. By adding to zero, they can be eliminated.



So to make the x coefficients equal in magnitude but opposite in sign, we need to multiply both x coefficients by some number to get them to an common number. So if we wanted to get -7 and 2 to some equal number, we could try to get them to the LCM.



Since the LCM of -7 and 2 is -14, we need to multiply both sides of the top equation by 2 and multiply both sides of the bottom equation by 7 like this:




2%28-7x%2By%29=2%288%29 Multiply the top equation (both sides) by 2
7%282x-y%29=7%282%29 Multiply the bottom equation (both sides) by 7




Distribute and multiply

-14x%2B2y=16
14x-7y=14


Now add the equations together. In order to add 2 equations, group like terms and combine them

%28-14x%2B14x%29%2B%282y-7y%29=16%2B14

Combine like terms and simplify



cross%28-14x%2B14x%29-5y=30 Notice how the x terms cancel out




-5y=30 Simplify




y=30%2F-5 Divide both sides by -5 to isolate y




y=-6 Reduce



Now plug this answer into the top equation -7x%2By=8 to solve for x

-7x%2By=8 Start with the first equation



-7x%2B%28-6%29=8 Plug in y=-6




-7x-6=8 Multiply



-7x=8%2B6Add 6 to both sides


-7x=14 Combine like terms on the right side


x=%2814%29%2F%28-7%29 Divide both sides by -7 to isolate x



x=-2 Divide




So our answer is
x=-2 and y=-6



which also looks like




Now let's graph the two equations (if you need help with graphing, check out this solver)


From the graph, we can see that the two equations intersect at . This visually verifies our answer.




graph of -7x%2By=8 (red) and 2x-y=2 (green) and the intersection of the lines (blue circle).



Linear-equations/133146: Solve the system of equations using the substitution method.
If the answer is a unique solution, present it as an ordered pair: (x, y). If not, specify whether the answer is “no solution” or “infinitely many solutions.”
-3x + y = 1
5x + 2y = -4

1 solutions

Answer 97341 by jim_thompson5910(28595) About Me  on 2008-03-21 17:59:35 (Show Source):
You can put this solution on YOUR website!


Start with the given system of equations:

system%28-3x%2By=1%2C5x%2B2y=-4%29



Now in order to solve this system by using substitution, we need to solve (or isolate) one variable. I'm going to solve for y.




So let's isolate y in the first equation

-3x%2By=1 Start with the first equation


y=1%2B3x Add 3x to both sides


y=%2B3x%2B1 Rearrange the equation


y=%28%2B3x%2B1%29%2F%281%29 Divide both sides by 1


y=%28%28%2B3%29%2F%281%29%29x%2B%281%29%2F%281%29 Break up the fraction


y=3x%2B1 Reduce



---------------------

Since y=3x%2B1, we can now replace each y in the second equation with 3x%2B1 to solve for x



5x%2B2highlight%28%283x%2B1%29%29=-4 Plug in y=3x%2B1 into the first equation. In other words, replace each y with 3x%2B1. Notice we've eliminated the y variables. So we now have a simple equation with one unknown.



5x%2B%282%29%283%29x%2B%282%29%281%29=-4 Distribute 2 to 3x%2B1


5x%2B6x%2B2=-4 Multiply


11x%2B2=-4 Combine like terms on the left side


11x=-4-2Subtract 2 from both sides


11x=-6 Combine like terms on the right side


x=%28-6%29%2F%2811%29 Divide both sides by 11 to isolate x



x=-6%2F11 Reduce





-----------------First Answer------------------------------


So the first part of our answer is: x=-6%2F11









Since we know that x=-6%2F11 we can plug it into the equation y=3x%2B1 (remember we previously solved for y in the first equation).



y=3x%2B1 Start with the equation where y was previously isolated.


y=3%28-6%2F11%29%2B1 Plug in x=-6%2F11


y=-18%2F11%2B1 Multiply


y=-7%2F11 Combine like terms (note: if you need help with fractions, check out this solver)



-----------------Second Answer------------------------------


So the second part of our answer is: y=-7%2F11









-----------------Summary------------------------------

So our answers are:

x=-6%2F11 and y=-7%2F11

which form the point



Linear-equations/133144: Find the equation, in standard form, with all integer coefficients, of the line perpendicular to x + 3y = 6 and passing through (-3, 5).

1 solutions

Answer 97340 by jim_thompson5910(28595) About Me  on 2008-03-21 17:58:19 (Show Source):
You can put this solution on YOUR website!
First convert the standard equation x%2B3y=6 into slope intercept form

Solved by pluggable solver: Converting Linear Equations in Standard form to Slope-Intercept Form (and vice versa)


1%2Ax%2B3%2Ay=6Start with the given equation



3%2Ay=6-1%2Ax Subtract 1%2Ax from both sides

y=%281%2F3%29%286-1%2Ax%29 Multiply both sides by 1%2F3

y=%281%2F3%29%286%29-%281%2F3%29%281%29x%29 Distribute 1%2F3

y=6%2F3-%281%2F3%29x Multiply

y=%28-1%2F3%29%2Ax%2B6%2F3 Rearrange the terms

y=%28-1%2F3%29%2Ax%2B2 Reduce any fractions

So the equation is now in slope-intercept form (y=mx%2Bb) where m=-1%2F3 (the slope) and b=2 (the y-intercept)





Now let's find the equation of the line that is perpendicular to y=%28-1%2F3%29x%2B2 which goes through (-3,5)

Solved by pluggable solver: Finding the Equation of a Line Parallel or Perpendicular to a Given Line


Remember, any two perpendicular lines are negative reciprocals of each other. So if you're given the slope of -1%2F3, you can find the perpendicular slope by this formula:

m%5Bp%5D=-1%2Fm where m%5Bp%5D is the perpendicular slope


m%5Bp%5D=-1%2F%28-1%2F3%29 So plug in the given slope to find the perpendicular slope



m%5Bp%5D=%28-1%2F1%29%283%2F-1%29 When you divide fractions, you multiply the first fraction (which is really 1%2F1) by the reciprocal of the second



m%5Bp%5D=3%2F1 Multiply the fractions.


So the perpendicular slope is 3



So now we know the slope of the unknown line is 3 (its the negative reciprocal of -1%2F3 from the line y=%28-1%2F3%29%2Ax%2B2). Also since the unknown line goes through (-3,5), we can find the equation by plugging in this info into the point-slope formula

Point-Slope Formula:

y-y%5B1%5D=m%28x-x%5B1%5D%29 where m is the slope and (x%5B1%5D,y%5B1%5D) is the given point



y-5=3%2A%28x%2B3%29 Plug in m=3, x%5B1%5D=-3, and y%5B1%5D=5



y-5=3%2Ax-%283%29%28-3%29 Distribute 3



y-5=3%2Ax%2B9 Multiply



y=3%2Ax%2B9%2B5Add 5 to both sides to isolate y

y=3%2Ax%2B14 Combine like terms

So the equation of the line that is perpendicular to y=%28-1%2F3%29%2Ax%2B2 and goes through (-3,5) is y=3%2Ax%2B14


So here are the graphs of the equations y=%28-1%2F3%29%2Ax%2B2 and y=3%2Ax%2B14




graph of the given equation y=%28-1%2F3%29%2Ax%2B2 (red) and graph of the line y=3%2Ax%2B14(green) that is perpendicular to the given graph and goes through (-3,5)





Now let's convert y=3x%2B14 to standard form


y-3x=14 Subtract 3x from both sides


-3x%2By=14 Rearrange the terms



So the equation that is perpendicular to x%2B3y=6 and goes through (-3,5) is

-3x%2By=14


Linear-equations/133143: Find the equation of the line that passes through the points (3, -2) and (4, -2).

1 solutions

Answer 97339 by jim_thompson5910(28595) About Me  on 2008-03-21 17:54:21 (Show Source):
You can put this solution on YOUR website!
First lets find the slope through the points (3,-2) and (4,-2)

m=%28y%5B2%5D-y%5B1%5D%29%2F%28x%5B2%5D-x%5B1%5D%29 Start with the slope formula (note: is the first point (3,-2) and is the second point (4,-2))

m=%28-2--2%29%2F%284-3%29 Plug in y%5B2%5D=-2,y%5B1%5D=-2,x%5B2%5D=4,x%5B1%5D=3 (these are the coordinates of given points)

m=+0%2F1 Subtract the terms in the numerator -2--2 to get 0. Subtract the terms in the denominator 4-3 to get 1


m=0 Reduce

So the slope is
m=0

------------------------------------------------


Now let's use the point-slope formula to find the equation of the line:



------Point-Slope Formula------
y-y%5B1%5D=m%28x-x%5B1%5D%29 where m is the slope, and is one of the given points

So lets use the Point-Slope Formula to find the equation of the line

y--2=%280%29%28x-3%29 Plug in m=0, x%5B1%5D=3, and y%5B1%5D=-2 (these values are given)


y%2B2=%280%29%28x-3%29 Rewrite y--2 as y%2B2


y%2B2=0x%2B%280%29%28-3%29 Distribute 0

y%2B2=0x%2B0 Multiply 0 and -3 to get 0%2F0. Now reduce 0%2F0 to get 0

y=0x%2B0-2 Subtract 2 from both sides to isolate y

y=-2 Combine like terms 0 and -2 to get -2
------------------------------------------------------------------------------------------------------------
Answer:


So the equation of the line which goes through the points (3,-2) and (4,-2) is:y=-2

The equation is now in y=mx%2Bb form (which is slope-intercept form) where the slope is m=0 and the y-intercept is b=-2

Notice if we graph the equation y=-2 and plot the points (3,-2) and (4,-2), we get this: (note: if you need help with graphing, check out this solver)

Graph of y=-2 through the points (3,-2) and (4,-2)

Notice how the two points lie on the line. This graphically verifies our answer.


Linear-equations/133142: Find the slope of the line that passes through the points (2, 3) and (5, 8).

1 solutions

Answer 97338 by jim_thompson5910(28595) About Me  on 2008-03-21 17:50:27 (Show Source):
You can put this solution on YOUR website!

Let's denote the first point (2,3) as . In other words, and

Now let's denote the second point (5,8) as . In other words, and



-------------------------



m=%28y%5B2%5D-y%5B1%5D%29%2F%28x%5B2%5D-x%5B1%5D%29 Start with the slope formula

m=%288-3%29%2F%285-2%29 Plug in y%5B2%5D=8,y%5B1%5D=3,x%5B2%5D=5,x%5B1%5D=2


m=5%2F3 Subtract the terms in the numerator 8-3 to get 5. Subtract the terms in the denominator 5-2 to get 3

---------------------
Answer:

So the slope of the line through the points (2,3) and (5,8) is m=5%2F3


Probability-and-statistics/133138: Find the value of the logarithm without using a calculator
In(e^5)
Thank you
1 solutions

Answer 97337 by jim_thompson5910(28595) About Me  on 2008-03-21 17:44:22 (Show Source):
You can put this solution on YOUR website!
ln%28e%5E5%29 Start with the given expression


5%2Aln%28e%29 Rewrite the expression using the identity ln%28x%5Ey%29=y%2Aln%28x%29


5%2A1 Replace ln%28e%29 with 1. Remember, ln%28e%29=1


5 Multiply


So ln%28e%5E5%29=5


Square-cubic-other-roots/133120: Please help me with this problem.
√(98x^3)
1 solutions

Answer 97330 by jim_thompson5910(28595) About Me  on 2008-03-21 16:15:45 (Show Source):
You can put this solution on YOUR website!

sqrt%2898x%5E3%29 Start with the given expression


sqrt%2898%29sqrt%28x%5E3%29 Break up the root


7%2Asqrt%282%29%2Asqrt%28x%5E3%29%29 Simplify sqrt%2898%29 to get 7%2Asqrt%282%29


7%2Asqrt%282%29%2Ax%2Asqrt%28x%29 Simplify sqrt%28x%5E3%29 to get x%2Asqrt%28x%29


7x%2Asqrt%282x%29 Combine the roots



----------------------------------
Answer:


So sqrt%2898x%5E3%29 simplifies to 7x%2Asqrt%282x%29

In other words, sqrt%2898x%5E3%29=7x%2Asqrt%282x%29 where every variable is positive


Polynomials-and-rational-expressions/133112: Find the following. Assume that variables can represent any real numbers.
sqrt ( a+4 )^2
The a+4 should be in parenthesis with an exponent of 2 in a radical sign. I hope I explained that correctly.
1 solutions

Answer 97328 by jim_thompson5910(28595) About Me  on 2008-03-21 15:59:10 (Show Source):
You can put this solution on YOUR website!
If you have something like x%5E2=4, how do you solve this? Well you simply take the square root of both sides like this

sqrt%28x%5E2%29=sqrt%284%29


x=0%2B-sqrt%284%29


Notice how sqrt%28x%5E2%29 simplifies to x. What's happening is the square root is undoing the square exponent.



---------------------


So the same thing is happening with sqrt%28+%28+a%2B4+%29%5E2%29. If you can't see it, then let x=a%2B4 to get

sqrt%28x%5E2%29


so this simplifies to x where x is positive


Now plug a%2B4 into x to get a%2B4



So this means that sqrt%28+%28+a%2B4+%29%5E2%29 simplifies to a%2B4 . In other words, sqrt%28+%28+a%2B4+%29%5E2%29=a%2B4 where a%2B4%3E0


real-numbers/133116: solve for x: 5(x-2)=2(10+x)
1 solutions

Answer 97323 by jim_thompson5910(28595) About Me  on 2008-03-21 15:51:28 (Show Source):
You can put this solution on YOUR website!

5%28x-2%29=2%2810%2Bx%29 Start with the given equation



5x-10=20%2B2x Distribute


5x=20%2B2x%2B10Add 10 to both sides


5x-2x=20%2B10 Subtract 2x from both sides


3x=20%2B10 Combine like terms on the left side


3x=30 Combine like terms on the right side


x=%2830%29%2F%283%29 Divide both sides by 3 to isolate x



x=10 Divide

--------------------------------------------------------------
Answer:
So our answer is x=10




Sequences-and-series/133104: This question is from textbook
Use inductive reasoning to predict the next TWO numbers in the sequence.
80, –40, 20, –10, 5, . . .
I can't figure out what the pattern is her necessarily.
i get that its -120 +60 -30 +15 but i don't get what comes next.
Help me out with this please.
1 solutions

Answer 97320 by jim_thompson5910(28595) About Me  on 2008-03-21 15:34:52 (Show Source):
You can put this solution on YOUR website!
Notice how each term is cut in half and is negated (ie the sign is changed). In other words, each term is multiplied by -1%2F2

Cut the 1st term 80 in half and negate it to get –40. In other words, %2880%29%28-1%2F2%29=-40

Cut the 2nd term –40 in half and negate it to get 20. In other words, %28-40%29%28-1%2F2%29=20

Cut the 3rd term 20 in half and negate it to get –10. In other words, %2820%29%28-1%2F2%29=-10

Cut the 4th term –10 in half and negate it to get 5. In other words, %28-10%29%28-1%2F2%29=5


So to find the next two terms, simply multiply the last few terms by -1%2F2


So lets multiply the last term 5 by -1%2F2

5%28-1%2F2%29=-5%2F2

So the next term is -5%2F2 or -2.5


Now lets multiply the last term -5%2F2 by -1%2F2

%28-5%2F2%29%28-1%2F2%29=5%2F4

So the next term is 5%2F4 or 1.25



So the updated sequence is

80, –40, 20, –10, 5, -5%2F2, 5%2F4


Polynomials-and-rational-expressions/133108: Factor completely.
252r^2 + 588rf + 343f^2
Thank you for any help you can give me in figuring this problem out.
1 solutions

Answer 97318 by jim_thompson5910(28595) About Me  on 2008-03-21 15:17:25 (Show Source):
You can put this solution on YOUR website!

252r%5E2%2B588rf%2B343f%5E2 Start with the given expression


7%2836r%5E2%2B84rf%2B49f%5E2%29 Factor out the GCF 7


Now let's focus on the inner expression 36r%5E2%2B84rf%2B49f%5E2




------------------------------------------------------------



Looking at 36r%5E2%2B84rf%2B49f%5E2 we can see that the first term is 36r%5E2 and the last term is 49f%5E2 where the coefficients are 36 and 49 respectively.

Now multiply the first coefficient 36 and the last coefficient 49 to get 1764. Now what two numbers multiply to 1764 and add to the middle coefficient 84? Let's list all of the factors of 1764:



Factors of 1764:
1,2,3,4,6,7,9,12,14,18,21,28,36,42,49,63,84,98,126,147,196,252,294,441,588,882

-1,-2,-3,-4,-6,-7,-9,-12,-14,-18,-21,-28,-36,-42,-49,-63,-84,-98,-126,-147,-196,-252,-294,-441,-588,-882 ...List the negative factors as well. This will allow us to find all possible combinations

These factors pair up and multiply to 1764
1*1764
2*882
3*588
4*441
6*294
7*252
9*196
12*147
14*126
18*98
21*84
28*63
36*49
42*42
(-1)*(-1764)
(-2)*(-882)
(-3)*(-588)
(-4)*(-441)
(-6)*(-294)
(-7)*(-252)
(-9)*(-196)
(-12)*(-147)
(-14)*(-126)
(-18)*(-98)
(-21)*(-84)
(-28)*(-63)
(-36)*(-49)
(-42)*(-42)

note: remember two negative numbers multiplied together make a positive number


Now which of these pairs add to 84? Lets make a table of all of the pairs of factors we multiplied and see which two numbers add to 84

First NumberSecond NumberSum
117641+1764=1765
28822+882=884
35883+588=591
44414+441=445
62946+294=300
72527+252=259
91969+196=205
1214712+147=159
1412614+126=140
189818+98=116
218421+84=105
286328+63=91
364936+49=85
424242+42=84
-1-1764-1+(-1764)=-1765
-2-882-2+(-882)=-884
-3-588-3+(-588)=-591
-4-441-4+(-441)=-445
-6-294-6+(-294)=-300
-7-252-7+(-252)=-259
-9-196-9+(-196)=-205
-12-147-12+(-147)=-159
-14-126-14+(-126)=-140
-18-98-18+(-98)=-116
-21-84-21+(-84)=-105
-28-63-28+(-63)=-91
-36-49-36+(-49)=-85
-42-42-42+(-42)=-84



From this list we can see that 42 and 42 add up to 84 and multiply to 1764


Now looking at the expression 36r%5E2%2B84rf%2B49f%5E2, replace 84rf with 42rf%2B42rf (notice 42rf%2B42rf adds up to 84rf. So it is equivalent to 84rf)

36r%5E2%2Bhighlight%2842rf%2B42rf%29%2B49f%5E2


Now let's factor 36r%5E2%2B42rf%2B42rf%2B49f%5E2 by grouping:


%2836r%5E2%2B42rf%29%2B%2842rf%2B49f%5E2%29 Group like terms


6r%286r%2B7f%29%2B7f%286r%2B7f%29 Factor out the GCF of 6r out of the first group. Factor out the GCF of 7f out of the second group


%286r%2B7f%29%286r%2B7f%29 Since we have a common term of 6r%2B7f, we can combine like terms

So 36r%5E2%2B42rf%2B42rf%2B49f%5E2 factors to %286r%2B7f%29%286r%2B7f%29


So this also means that 36r%5E2%2B84rf%2B49f%5E2 factors to %286r%2B7f%29%286r%2B7f%29 (since 36r%5E2%2B84rf%2B49f%5E2 is equivalent to 36r%5E2%2B42rf%2B42rf%2B49f%5E2)


note: %286r%2B7f%29%286r%2B7f%29 is equivalent to %286r%2B7f%29%5E2 since the term 6r%2B7f occurs twice. So 36r%5E2%2B84rf%2B49f%5E2 also factors to %286r%2B7f%29%5E2



------------------------------------------------------------




So our expression goes from 7%2836r%5E2%2B84rf%2B49f%5E2%29 and factors further to 7%286r%2B7f%29%5E2


------------------
Answer:

So 252r%5E2%2B588rf%2B343f%5E2 factors to 7%286r%2B7f%29%5E2


Polynomials-and-rational-expressions/133110: Express using a positive exponent.
r^-2
Would it just be r^2? That would seem to be too simple.
1 solutions

Answer 97317 by jim_thompson5910(28595) About Me  on 2008-03-21 15:16:25 (Show Source):
You can put this solution on YOUR website!
You're close, but r%5E%28-2%29=1%2Fr%5E2 where r%3C%3E0


Polynomials-and-rational-expressions/133109: Multiply.
(r + p)(r^2 - rp + p^2)

1 solutions

Answer 97316 by jim_thompson5910(28595) About Me  on 2008-03-21 15:15:38 (Show Source):
You can put this solution on YOUR website!

%28r%2Bp%29%28r%5E2-rp%2Bp%5E2%29 Start with the given expression



r%28r%5E2-rp%2Bp%5E2%29%2Bp%28r%5E2-rp%2Bp%5E2%29 Expand the expression. Remember something like %28a%2Bb%29%28c%2Bd%2Be%29 expands to a%28c%2Bd%2Be%29%2Bb%28c%2Bd%2Be%29


Distribute


r%5E3-r%5E2p%2Brp%5E2%2Bpr%5E2-p%5E2r%2Bp%5E3 Multiply


r%5E3%2Bp%5E3 Combine like terms



So %28r%2Bp%29%28r%5E2-rp%2Bp%5E2%29 expands and simplifies to r%5E3%2Bp%5E3.

In other words, %28r%2Bp%29%28r%5E2-rp%2Bp%5E2%29=r%5E3%2Bp%5E3


Quadratic_Equations/133089: Find the vertex and intercepts for h(x)= -x^2-2x+8 and sketch the graph?
1 solutions

Answer 97307 by jim_thompson5910(28595) About Me  on 2008-03-21 13:23:05 (Show Source):
You can put this solution on YOUR website!
Vertex:

To find the vertex, we first need to find the axis of symmetry (ie the x-coordinate of the vertex)
To find the axis of symmetry, use this formula:

x=-b%2F%282a%29

From the equation y=-x%5E2-2x%2B8 we can see that a=-1 and b=-2

x=%28--2%29%2F%282%2A-1%29 Plug in b=-2 and a=-1


x=2%2F%282%2A-1%29 Negate -2 to get 2


x=%282%29%2F-2 Multiply 2 and -1 to get -2



x=-1 Reduce


So the axis of symmetry is x=-1


So the x-coordinate of the vertex is x=-1. Lets plug this into the equation to find the y-coordinate of the vertex.


Lets evaluate f%28-1%29

f%28x%29=-x%5E2-2x%2B8 Start with the given polynomial


f%28-1%29=-%28-1%29%5E2-2%28-1%29%2B8 Plug in x=-1


f%28-1%29=-%281%29-2%28-1%29%2B8 Raise -1 to the second power to get 1


f%28-1%29=-%281%29--2%2B8 Multiply 2 by -1 to get -2


f%28-1%29=-1%2B2%2B8 Negate any negatives


f%28-1%29=9 Now combine like terms


So the vertex is (-1,9)







Intercepts:

Y-intercept:

To find the y-intercept, simply plug in x=0 and simplify



f%28x%29=-1x%5E2-2x%2B8 Start with the given function


f%280%29=-1%280%29%5E2-2%280%29%2B8 Plug in x=0


f%280%29=-1%2A0-2%2A0%2B8 Raise 0 to the 2nd power to get 0


f%280%29=0-2%2A0%2B8 Multiply -1 and 0 to get 0


f%280%29=0-0%2B8 Multiply 2 and 0 to get 0


f%280%29=0%2B8 Subtract 0 from 0 to get 0


f%280%29=8 Add 0 and 8 to get 8


So when x=0, we have y=8 which means that the y-intercept is (0,8)




X-intercept:

To find the x-intercept, plug in y=0 and solve for x


-x%5E2-2x%2B8=0 Start with the given equation

%28-x-4%29%28x-2%29=0 Factor the left side (note: if you need help with factoring, check out this solver)



Now set each factor equal to zero:
-x-4=0 or x-2=0

x=-4 or x=2 Now solve for x in each case


So our answer is
x=-4 or x=2


which means that the x-intercepts are

(-4,0) and (2,0)



--------------------------------------------

Notice if we graph y=-x%5E2-2x%2B8, we can visually verify our answer


+graph%28+500%2C+500%2C-10%2C+10%2C+-10%2C+10%2C+-x%5E2-2x%2B8%29+


Quadratic_Equations/133088: solve by completing the square 2m^2-m-15=0?
1 solutions

Answer 97305 by jim_thompson5910(28595) About Me  on 2008-03-21 13:16:58 (Show Source):
You can put this solution on YOUR website!
y=2+x%5E2-1+x-15 Start with the given equation


y%2B15=2+x%5E2-1+x Add 15 to both sides


y%2B15=2%28x%5E2%2B%28-1%2F2%29x%29 Factor out the leading coefficient 2


Take half of the x coefficient -1%2F2 to get -1%2F4 (ie %281%2F2%29%28-1%2F2%29=-1%2F4).

Now square -1%2F4 to get 1%2F16 (ie %28-1%2F4%29%5E2=%28-1%2F4%29%28-1%2F4%29=1%2F16)




y%2B15=2%28x%5E2%2B%28-1%2F2%29x%2B1%2F16-1%2F16%29 Now add and subtract this value inside the parenthesis. Doing both the addition and subtraction of 1%2F16 does not change the equation



y%2B15=2%28%28x-1%2F4%29%5E2-1%2F16%29 Now factor x%5E2%2B%28-1%2F2%29x%2B1%2F16 to get %28x-1%2F4%29%5E2


y%2B15=2%28x-1%2F4%29%5E2-2%281%2F16%29 Distribute


y%2B15=2%28x-1%2F4%29%5E2-1%2F8 Multiply


y=2%28x-1%2F4%29%5E2-1%2F8-15 Now add %2B15 to both sides to isolate y


y=2%28x-1%2F4%29%5E2-121%2F8 Combine like terms



2%28x-1%2F4%29%5E2-121%2F8=0 Now to solve for x, let y=0


2%28x-1%2F4%29%5E2=%2B121%2F8 Add 121%2F8 to both sides


%28x-1%2F4%29%5E2=%28121%2F8%29%2F%282%29 Divide both sides by 2


%28x-1%2F4%29%5E2=121%2F16 Reduce


Take the square root of both sides



Take the square root of 121 to get 11. Take the square root of 16 to get 4.


Add 1%2F4 to both sides


Break up the expression

or



Combine the fractions

or


Combine like terms


or



Reduce


or




----------------------------------------

Answer:
So our solution is


or