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logarithm/198851: Express as a single logarithm
1/2 Log a X + 3 Log a Y - 2 Log a X

1 solutions

Answer 149336 by jim_thompson5910(28595) About Me  on 2009-06-03 17:14:24 (Show Source):
You can put this solution on YOUR website!
%281%2F2%29log%28a%2C%28x%29%29%2B3%2Alog%28a%2C%28y%29%29-2%2Alog%28a%2C%28x%29%29 Start with the given expression.


log%28a%2C%28x%5E%281%2F2%29%29%29%2Blog%28a%2C%28y%5E3%29%29-log%28a%2C%28x%5E2%29%29 Rewrite the logs using the identity y%2Alog%28b%2C%28x%29%29=log%28b%2C%28x%5Ey%29%29


log%28a%2C%28sqrt%28x%29%29%29%2Blog%28a%2C%28y%5E3%29%29-log%28a%2C%28x%5E2%29%29 Convert to radical notation.


log%28a%2C%28sqrt%28x%29%2Ay%5E3%29%29-log%28a%2C%28x%5E2%29%29 Combine the first two logs using the identity log%28b%2C%28A%29%29%2Blog%28b%2C%28B%29%29=log%28b%2C%28A%2AB%29%29


log%28a%2C%28%28sqrt%28x%29%2Ay%5E3%29%2F%28x%5E2%29%29%29 Combine the logs using the identity log%28b%2C%28A%29%29-log%28b%2C%28B%29%29=log%28b%2C%28A%2FB%29%29


So


Probability-and-statistics/198806: from a group of 6 men and 4 women, a committee of 3 is to be selected at random. find P(at least 2 women)
1 solutions

Answer 149335 by jim_thompson5910(28595) About Me  on 2009-06-03 17:10:34 (Show Source):
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Simply find the probability of 2 women or 3 women. In other words,


P(at least 2 women) = P(2 women) + P(3 women)


Geometric_formulas/198800: This question is from textbook geometry
can you please help me answer the following ((( What is the locus of points in a plane that are equidistant from points A and B in the plane? )))
1 solutions

Answer 149334 by jim_thompson5910(28595) About Me  on 2009-06-03 17:08:15 (Show Source):
You can put this solution on YOUR website!
The locus of points in a plane that are equidistant from points A and B in the plane is a line that is the perpendicular bisector to line that connects the two points.


Linear-equations/198850: solving x-y=6 for y results in y=-x+6

1 solutions

Answer 149331 by jim_thompson5910(28595) About Me  on 2009-06-03 16:51:00 (Show Source):
You can put this solution on YOUR website!
x-y=6 Start with the given equation.


-y=6-x Subtract x from both sides.


-y=-x%2B6 Rearrange the terms.


y=%28-x%2B6%29%2F%28-1%29 Divide both sides by -1 to isolate y.


y=%28-x%29%2F%28-1%29%2B%286%29%2F%28-1%29 Break up the fraction.


y=x-6 Reduce.


Mixture_Word_Problems/198832: How much soil containing 45% sand do you need to add 1ft of soil containing 15% sand in order to make a soil containing 35% sand?
1 solutions

Answer 149330 by jim_thompson5910(28595) About Me  on 2009-06-03 16:46:00 (Show Source):
You can put this solution on YOUR website!
This question has been answered here.

Edit:

From the previous solution, the given equation is 0.45x+%2B+0.15+=+0.35%28x+%2B+1%29


0.45x+%2B+0.15+=+0.35%28x+%2B+1%29 Start with the given equation.


0.45x+%2B+0.15+=+0.35x+%2B+0.35 Distribute


100%280.45x%2B0.15%29=100%280.35x%2B0.35%29 Multiply both sides by 100 to clear out the decimals.


45x%2B15=35x%2B35 Distribute and multiply.


45x=35x%2B35-15 Subtract 15 from both sides.


45x-35x=35-15 Subtract 35x from both sides.


10x=35-15 Combine like terms on the left side.


10x=20 Combine like terms on the right side.


x=%2820%29%2F%2810%29 Divide both sides by 10 to isolate x.


x=2 Reduce.


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

Answer:

So the solution is x=2 which means that you need 2 cubic feet of soil containing 45% sand.


Probability-and-statistics/198845: At Ajax Spring Water, a half-liter bottle of soft drink is supposed to contain a mean of 520 ml. The filling process follows a normal distribution with a known process standard deviation of 4 ml. (a) Which sampling distribution would you use if random samples of 10 bottles are to be weighed? Why? (b) Set up hypotheses and a two-tailed decision rule for the correct mean using the 5 percent level of significance. (c) If a sample of 16 bottles shows a mean fill of 515 ml, does this contradict the hypothesis that the true mean is 520 ml?
1 solutions

Answer 149329 by jim_thompson5910(28595) About Me  on 2009-06-03 16:42:19 (Show Source):
You can put this solution on YOUR website!
This question has already been answered here.


Numbers_Word_Problems/198849: An express train and a local train both leave Gray's Lake at 12:00 noon and head for Chicago 60 miles away. The express travels twice as fast as the local and arrives 2 hours ahead of it.Find the speed of each train.
60m/2h= t + 12n
I cannot get the right answer.
1 solutions

Answer 149328 by jim_thompson5910(28595) About Me  on 2009-06-03 16:40:14 (Show Source):
You can put this solution on YOUR website!
Let t%5B1%5D time of express train and t%5B2%5D time of local train

Also, let r%5B1%5D speed of express train and r%5B2%5D speed of local train


Since the "express train travels twice as fast as the local train", this means that r%5B1%5D=2%2Ar%5B2%5D


Also, because "the express train arrives 2 hours ahead of the local train", this tells us t%5B1%5D=t%5B2%5D-2



Now let's set up the formula for the local train:


d=rt Start with the distance rate time formula


60=r%5B2%5D%2At%5B2%5D Plug in d=60, r=r%5B2%5D and t=t%5B2%5D


60%2Ft%5B2%5D=r%5B2%5D Divide both sides by t%5B2%5D.


So after isolating the second speed, we get r%5B2%5D=60%2Ft%5B2%5D



Now let's set up the formula for the express train:


d=rt Start with the distance rate time formula


60=r%5B1%5D%2At%5B1%5D Plug in d=60, r=r%5B1%5D and t=t%5B1%5D


60=%282%2Ar%5B2%5D%29%2A%28t%5B2%5D-2%29 Plug in r%5B1%5D=2%2Ar%5B2%5D and t%5B1%5D=t%5B2%5D-2


60=%282%2A%2860%2Ft%5B2%5D%29%29%2A%28t%5B2%5D-2%29 Plug in r%5B2%5D=60%2Ft%5B2%5D


60=%28120%2Ft%5B2%5D%29%2A%28t%5B2%5D-2%29 Multiply


60t%5B2%5D=120%28t%5B2%5D-2%29 Multiply both sides by t%5B2%5D.


60t%5B2%5D=120t%5B2%5D-240 Distribute


60t%5B2%5D-120t%5B2%5D=-240 Subtract 120t%5B2%5D from both sides.


-60t%5B2%5D=-240 Combine like terms.


t%5B2%5D=-240%2F%28-60%29 Divide both sides by -60 to isolate t%5B2%5D.


t%5B2%5D=4 Divide


So it takes 4 hours for the local train


60=r%5B2%5D%2At%5B2%5D Go back to the local train formula


60=r%5B2%5D%2A4 Plug in t%5B2%5D=4


60%2F4=r%5B2%5D Divide both sides by 4.


15=r%5B2%5D Divide.


So the speed of the local train is 15 mph

Now simply double the speed of the local train to get 15%2A2=30

So the speed of the local train is 15 mph and the speed of the express train is 30 mph.



Note: nowhere in the solution above is a mention of 12:00 noon. This information is unnecessary and it is put in there to throw you off.


Polynomials-and-rational-expressions/198848: please help me solve this

8y^4+12y^2-176 divided by 2y-4
1 solutions

Answer 149327 by jim_thompson5910(28595) About Me  on 2009-06-03 16:28:06 (Show Source):
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%288y%5E4%2B12y%5E2-176%29%2F%282y-4%29 Start with the given expression.


%284%28y-2%29%28y%2B2%29%282y%5E2%2B11%29%29%2F%282y-4%29 Factor the numerator


%284%28y-2%29%28y%2B2%29%282y%5E2%2B11%29%29%2F%282%28y-2%29%29 Factor the denominator


%282%2A2%28y-2%29%28y%2B2%29%282y%5E2%2B11%29%29%2F%282%28y-2%29%29 Factor 4 to get 2*2


Cancel out the common terms.


2%28y%2B2%29%282y%5E2%2B11%29 Simplify


4y%5E3%2B22y%2B8y%5E2%2B44 Expand and multiply


So %288y%5E4%2B12y%5E2-176%29%2F%282y-4%29=4y%5E3%2B22y%2B8y%5E2%2B44 where y%3C%3E2


Surface-area/198847: This question is from textbook
Directions state: Find the perimeters and areas of the squares and rectangles in questions 7-10.
The figure shown in the text has a picture of a square which is dissected in the middle to form two right triangles. The triangle has two 45 degree and one 90 degree angles. All that is given is six square root of two (6 square root 2) for the hypotenuse of the adjacent right triangles. My apoogies but I do not have a square root symbol key on my computer keyboard. As you can tell I need to solve for the perimeter and area, but I do not even know how to without data given for either side one or side two.
1 solutions

Answer 149325 by jim_thompson5910(28595) About Me  on 2009-06-03 16:11:37 (Show Source):
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If we just focus on one triangle, we get




To find the unknown length, we need to use the Pythagorean Theorem.


Remember, the Pythagorean Theorem is a%5E2%2Bb%5E2=c%5E2 where "a" and "b" are the legs of a triangle and "c" is the hypotenuse.


Since the legs are x and x (ie the legs are equal) this means that a=x and b=x


Also, since the hypotenuse is 6%2Asqrt%282%29, this means that c=6%2Asqrt%282%29.


a%5E2%2Bb%5E2=c%5E2 Start with the Pythagorean theorem.


x%5E2%2Bx%5E2=%286%2Asqrt%282%29%29%5E2 Plug in a=x, b=2, c=6%2Asqrt%282%29


x%5E2%2Bx%5E2=72 Square 6%2Asqrt%282%29 to get .


2x%5E2=72 Combine like terms.


x%5E2=72%2F2 Divide both sides by 2.


x%5E2=36 Reduce


x=sqrt%2836%29 Take the square root of both sides. Note: only the positive square root is considered (since a negative length doesn't make sense).


x=6 Evaluate the square root of 36 to get 6


So the side length of the square is 6 units.


Now simply plug this side length into the following formulas (note: "s" is the length of the side of the square):


Perimeter: P=4s=4%286%29=24. So the perimeter is 24 units.

Area: P=s%5E2=%286%29%5E2=36. So the area is 36 square units.


Linear-equations/198846: state the x and y-intercept of y=4x-7
1 solutions

Answer 149319 by jim_thompson5910(28595) About Me  on 2009-06-03 15:40:06 (Show Source):
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x-intercept


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


y=4x-7 Start with the given equation.


0=4x-7 Plug in y=0.


-4x=-7 Subtract 4x from both sides.


x=%28-7%29%2F%28-4%29 Divide both sides by -4 to isolate x.


x=7%2F4 Reduce.


So the x-intercept is .


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


y-intercept


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


y=4x-7 Start with the given equation.


y=4%280%29-7 Plug in x=0.


y=0-7 Multiply -4 and 0 to get 0.


y=-7 Simplify.


So the y-intercept is .


Linear-equations/198844: what is the x-intercept of the line 4x+y=4
1 solutions

Answer 149318 by jim_thompson5910(28595) About Me  on 2009-06-03 15:36:19 (Show Source):
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x-intercept


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


4x%2By=4 Start with the given equation.


4x%2B0=4 Plug in y=0.


4x=4 Simplify.


x=%284%29%2F%284%29 Divide both sides by 4 to isolate x.


x=1 Reduce.


So the x-intercept is .


Linear-systems/198842: Please help me solve:
Soybean meal is 14% protein; cornmeal is 7% protein. How many pounds of each should be mixed together in order to get 280lbs mixture that is 12% protein?
How many pounds of the cornmeal should be in the misture?
How many pounds of the soybean should be in the mixture?
Thank you.
1 solutions

Answer 149317 by jim_thompson5910(28595) About Me  on 2009-06-03 15:35:16 (Show Source):
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let x= # of pounds of soybean meal and y=# of pounds of cornmeal

Since we want a 280 lbs mixture, this means that we have the first equation:
x%2By=280


Also, because we want a "280-lb mixture that is 12% protein" from the mixture of
soybean meal that is 14% protein and cornmeal that is 7% protein, we have the second equation: 0.14x%2B0.07y=280%280.12%29



0.14x%2B0.07y=280%280.12%29 Start with the second equation.


0.14x%2B0.07y=33.6 Multiply


10%280.14x%2B0.07y%29=10%2833.6%29 Multiply both sides by 100 to remove the decimals


14x%2B7y=3360 Distribute


So we have the new system of equations:

system%28x%2By=280%2C14x%2B7y=3360%29


Let's solve the system by use of substitution


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%2By=280 Start with the first equation


y=280-x Subtract x from both sides


y=-x%2B280 Rearrange the equation


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

Since y=-x%2B280, we can now replace each y in the second equation with -x%2B280 to solve for x



14x%2B7highlight%28%28-x%2B280%29%29=3360 Plug in y=-x%2B280 into the second equation. In other words, replace each y with -x%2B280. Notice we've eliminated the y variables. So we now have a simple equation with one unknown.



14x%2B%287%29%28-1%29x+%2B+%287%29%28280%29=3360 Distribute 7 to -x%2B280


14x-7x%2B1960=3360 Multiply


7x%2B1960=3360 Combine like terms on the left side


7x=3360-1960Subtract 1960 from both sides


7x=1400 Combine like terms on the right side


x=%281400%29%2F%287%29 Divide both sides by 7 to isolate x


x=200 Divide



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


So the first part of our answer is: x=200



Since we know that x=200 we can plug it into the equation y=-x%2B280 (remember we previously solved for y in the first equation).



y=-x%2B280 Start with the equation where y was previously isolated.


y=-%28200%29%2B280 Plug in x=200


y=-200%2B280 Multiply


y=80 Combine like terms



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


So the second part of our answer is: y=80






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

So our answers are:

x=200 and y=80 which form the ordered pair (200,80)



So 200 pounds of soybean meal and 80 pounds of cornmeal are needed for the mixture.





Linear-equations/198841: find both intercepts of the line 3x+4y=-12
1 solutions

Answer 149316 by jim_thompson5910(28595) About Me  on 2009-06-03 15:26:25 (Show Source):
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x-intercept


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


3x%2B4y=-12 Start with the given equation.


3x%2B4%280%29=-12 Plug in y=0.


3x%2B0=-12 Multiply 4 and 0 to get 0.


3x=-12 Simplify.


x=%28-12%29%2F%283%29 Divide both sides by 3 to isolate x.


x=-4 Reduce.


So the x-intercept is .


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


y-intercept


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


3x%2B4y=-12 Start with the given equation.


3%280%29%2B4y=-12 Plug in x=0.


0%2B4y=-12 Multiply 3 and 0 to get 0.


4y=-12 Simplify.


y=%28-12%29%2F%284%29 Divide both sides by 4 to isolate y.


y=-3 Reduce.


So the y-intercept is .


Notice that if we graph the equation 3x%2B4y=-12, we can see that the graph has the x-intercept and the y-intercept


Graph of 3x%2B4y=-12


Linear-equations/198840: fine the slope of the line that contains (4,5) and (4,4)
1 solutions

Answer 149315 by jim_thompson5910(28595) About Me  on 2009-06-03 15:20:33 (Show Source):
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Note: is the first point and is the second point .


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


m=%284-5%29%2F%284-4%29 Plug in y%5B2%5D=4, y%5B1%5D=5, x%5B2%5D=4, and x%5B1%5D=4


m=%28-1%29%2F%284-4%29 Subtract 5 from 4 to get -1


m=%28-1%29%2F%280%29 Subtract 4 from 4 to get 0


Remember, you cannot divide by zero. So this means that the slope is undefined.


Linear-equations/198839: Rewrite the equation in slope-intercept form. 8x-3y-5=0
1 solutions

Answer 149313 by jim_thompson5910(28595) About Me  on 2009-06-03 15:15:55 (Show Source):
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8x-3y-5=0 Start with the given equation.


8x-3y=5 Add 5 to both sides.


-3y=5-8x Subtract 8x from both sides.


-3y=-8x%2B5 Rearrange the terms.


y=%28-8x%2B5%29%2F%28-3%29 Divide both sides by -3 to isolate y.


y=%28%28-8%29%2F%28-3%29%29x%2B%285%29%2F%28-3%29 Break up the fraction.


y=%288%2F3%29x-5%2F3 Reduce.


So the equation y=%288%2F3%29x-5%2F3 is now in slope intercept form y=mx%2Bb where the slope is m=8%2F3 and the y-intercept is b=-5%2F3


note: the y-intercept is the point


Linear-equations/198838: Find the slope and y-intercept of the line 6x-3y=72
1 solutions

Answer 149312 by jim_thompson5910(28595) About Me  on 2009-06-03 15:08:58 (Show Source):
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6x-3y=72 Start with the given equation.


-3y=72-6x Subtract 6x from both sides.


-3y=-6x%2B72 Rearrange the terms.


y=%28-6x%2B72%29%2F%28-3%29 Divide both sides by -3 to isolate y.


y=%28%28-6%29%2F%28-3%29%29x%2B%2872%29%2F%28-3%29 Break up the fraction.


y=2x-24 Reduce.


So the equation y=2x-24 is now in slope intercept form y=mx%2Bb where the slope is m=2 and the y-intercept is b=-24

note: the y-intercept is the point


Equations/198836: A firm prints advertising leaflets. They have a set-up fee of £100 and charge 5p per leaflet. Explain in words how to find the total cost of printing N leaflets. Hence explain why the total cost £(C) is given by the formula
C = 100 + 0.05N.
I am sorry to ask for help but I have never been very good with algebra and I am still awaiting a battery for my TI84.
1 solutions

Answer 149308 by jim_thompson5910(28595) About Me  on 2009-06-03 14:45:39 (Show Source):
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No matter how many leaflets you buy, you will pay at least £100. So that's why the constant cost of 100 is in there. Any leaflets you buy, you'll be paying 0.05 (or 5%) of a pound per leaflet. So this is why 0.05N is added.


Here are some examples:

If you buy 100 leaflets, then N=100 and...

C = 100 + 0.05(100) = 100 + 5 = 105

So the total cost is £105



Or if you buy 300 leaflets, then N=300 and...

C = 100 + 0.05(300) = 100 + 15 = 115

So the total cost is £115


logarithm/198808: Hello!
A function f(x) is given.
f(x) = log5(log10(x))
(a) Find the domain of the function f
(b) Find the inverse function of f.
f -1(x) =
thanks for your help!

1 solutions

Answer 149307 by jim_thompson5910(28595) About Me  on 2009-06-03 14:33:20 (Show Source):
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a)

Since you cannot take the log of 0 or a negative value, this means that log%2810%2C%28x%29%29%3E0 and x%3E0 (for the outer and inner logs)


If we solve log%2810%2C%28x%29%29%3E0, we get x%3E1. So combining the inequalities x%3E0 and x%3E1 (ie perform a set union), we get x%3E1.

So the domain of f%28x%29=log%285%2C%28log%2810%2C%28x%29%29%29%29 is x%3E1


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

b)

f%28x%29=log%285%2C%28log%2810%2C%28x%29%29%29%29 Start with the given function.


y=log%285%2C%28log%2810%2C%28x%29%29%29%29 Replace f(x) with "y"


x=log%285%2C%28log%2810%2C%28y%29%29%29%29 Switch each x and y


5%5Ex=log%2810%2C%28y%29%29 Rewrite the equation using the property: log%28b%2C%28x%29%29=y ====> b%5Ey=x


10%5E%285%5Ex%29=y Rewrite the equation again using the property: log%28b%2C%28x%29%29=y ====> b%5Ey=x


So the inverse function is



Probability-and-statistics/198810: Write two data sets with a range equal to 35 but with different standard deviations. You do not need to calculate the standard deviations.
1 solutions

Answer 149305 by jim_thompson5910(28595) About Me  on 2009-06-03 14:23:04 (Show Source):
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Data Set #1: 1, 5, 33, 36

Range = 36 - 1 = 35
Standard Deviation is relatively large (since the data values are spread out)



Data Set #2: 1, 2, 4, 7, 9, 12, 13, 14, 16, 19, 20, 21, 25, 27, 29, 30, 31, 34, 35, 36

Range = 36 - 1 = 35
Now the standard deviation is slightly smaller (since the data values are closer together)




Probability-and-statistics/198815: A set of data with a mean of 58 and a standard deviation of 6.3 is normally distributed. Find the value that is 2 standard deviations below the mean. Round your answer to the nearest tenth.
1 solutions

Answer 149303 by jim_thompson5910(28595) About Me  on 2009-06-03 14:16:33 (Show Source):
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Simply subtract 2 times the standard deviation from the mean to get:


58-2*6.3=58-12.6=45.4


So the value that is 2 standard deviations below the mean is 45.4


Geometric_formulas/198799: This question is from textbook geometry
can you please help me answer the following ((( What is the locus of points in space that are equidistant from two parellel planes? )))
1 solutions

Answer 149302 by jim_thompson5910(28595) About Me  on 2009-06-03 14:14:25 (Show Source):
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If you either draw a picture or hold up two sheets of paper (for the two planes), you'll see that the locus of points form a third plane that is right in the middle of the two parallel planes.


Quadratic_Equations/198828: Write three quadratic equations, with a, b, and c (coefficients of x2, x, and the constant) as:
Integers
Rational numbers
Irrational numbers
I don't understand how to set these up... can someone give me some examples and explanations so i can form my own equations?
1 solutions

Answer 149301 by jim_thompson5910(28595) About Me  on 2009-06-03 14:11:06 (Show Source):
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1. Integers: any whole number
Let a=2, b=6, c=-12 (which are all whole numbers)
y=2x%5E2%2B6x-12


2. Rational Number: any number that is a ratio (or fraction) of two integers. So 1%2F4 and 2%2F1 are rational numbers
Let a=1%2F4,b=1%2F2, c=-1%2F12 (which are all fractions of whole numbers)

y=%281%2F4%29x%5E2%2B%281%2F2%29x-1%2F12

3. Irrational number: any number that cannot be represented by a fraction of two integers. For example pi and sqrt%2837%29 are irrational numbers

a=sqrt%2815%29, b=pi, c=sqrt%2812%29,

y=sqrt%2815%29x%5E2%2Bpi%2Ax%2Bsqrt%2812%29,


Functions/198829: What kind of function is, Y= -2x squared + 1?
1 solutions

Answer 149300 by jim_thompson5910(28595) About Me  on 2009-06-03 14:09:30 (Show Source):
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The function f%28x%29=-2x%5E2%2B1 is a quadratic polynomial function.


Quadratic_Equations/198830: Joe has a collection of nickels and dimes that is worth $6.05. If the number of dimes was doubled and number of nickels was decreaseed by 10, the value of the coins would be $9.85. how many dimes does he have?
f(x) = ax^2 + bx + c = 0
using this formula I cannot figure the answer out. please help.
1 solutions

Answer 149299 by jim_thompson5910(28595) About Me  on 2009-06-03 14:08:48 (Show Source):
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This question has been answered here. Did you have any questions about it?


Probability-and-statistics/198809: Use the following set of values for exercises 8–13.
0.3 0.6 0.9 1.3 0.4 0.6 1.2 1.4 1.1 0.2 0.2

please Find the mean, median, and mode(s) of the data set. Round answers to the nearest hundredth, if necessary.
1. Find the range.
2. Find the interquartile range.
3. Find the standard deviation. Round to the nearest hundredth.
4. Find the 25th and 75th percentiles.

thanks for helping me out!
1 solutions

Answer 149297 by jim_thompson5910(28595) About Me  on 2009-06-03 14:05:51 (Show Source):
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First sort the numbers into ascending order (from least to greatest):
0.2,0.2,0.3,0.4,0.6,0.6,0.9,1.1,1.2,1.3,1.4


Range:

To find the range, subtract the smallest number (in this case 0.2) from the largest number (in this case 1.4) like this:


Range=1.4-0.2=1.2

So the range is 1.2






Interquartile Range:


First, find the median for the first half of the data set (ignore the median):


Median of 0.2, 0.2, 0.3, 0.4, 0.6 is 0.3 (since this is the middle most value)


Now find the median of the last half of the data set (ignore the median):


Median of 0.9, 1.1, 1.2, 1.3, 1.4 is 1.2 (since this is the middle most value)


So the 1st and 3rd quartiles are 0.3 and 1.2 respectively.


This means that the interquartile range is

1.2 - 0.3 = 0.9


Note: the interquartile range is the difference between the 1st and 3rd quartiles






Note: I'm assuming that you want the sample standard deviation.


Standard Deviation:


Step 1) Find the mean:






So the mean is roughly 0.75 (rounded to the nearest hundredth).


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


Step 2) Find the differences between the mean and every value:


Now subtract EVERY value from the mean (0.75) to get:
0.2-0.75 = -0.55, 0.2-0.75 = -0.55, 0.3-0.75 = -0.45, 0.4-0.75 = -0.35, 0.6-0.75 = -0.15, 0.6-0.75 = -0.15, 0.9-0.75 = 0.15, 1.1-0.75 = 0.35, 1.2-0.75 = 0.45, 1.3-0.75 = 0.55, 1.4-0.75 = 0.65,


So you should have a new column of values:
-0.55, -0.55, -0.45, -0.35, -0.15, -0.15, 0.15, 0.35, 0.45, 0.55, 0.65,
----------------------------------------------------------


Step 3) Squaring the differences:


Now square EVERY value in the last column to get:
(-0.55)^2 = 0.3, (-0.55)^2 = 0.3, (-0.45)^2 = 0.2, (-0.35)^2 = 0.12, (-0.15)^2 = 0.02, (-0.15)^2 = 0.02, (0.15)^2 = 0.02, (0.35)^2 = 0.12, (0.45)^2 = 0.2, (0.55)^2 = 0.3, (0.65)^2 = 0.42,


So you should have a new column of values:
0.3, 0.3, 0.2, 0.12, 0.02, 0.02, 0.02, 0.12, 0.2, 0.3, 0.42,
----------------------------------------------------------


Step 4) Adding up the squares:


Now add up the values of the last column:
0.3 + 0.3 + 0.2 + 0.12 + 0.02 + 0.02 + 0.02 + 0.12 + 0.2 + 0.3 + 0.42 = 2.02

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

Step 5) Divide the sum by n-1:


Divide that sum by one less than the number of values in the list (in this case, it is n-1=11-1=10).


2.02%2F%2811-1%29=0.202


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


Step 6) Take the square root of the quotient:


Take the square root of 0.202 to get sqrt%280.202%29=0.449444101084885


Now round to the nearest hundredth to get 0.45.


So the standard deviation is roughly 0.45.





If you don't like that method, then here's another way:


First sort the numbers into ascending order (from least to greatest):
0.2,0.2,0.3,0.4,0.6,0.6,0.9,1.1,1.2,1.3,1.4


Standard Deviation: where is the average, is the ith number, and is the number of numbers

So we can replace N with 11



Subtract 11-1 to get 10



Replace with 0.75



Expand the summation (replace each x%5Bi%5D with the respective number)




Subtract the terms in the parenthesis



Square each term



Add up all of the terms

sqrt%28%281%2F10%292.0475%29

Multiply

sqrt%280.20475%29

Take the square root

0.452493093869951


Round to the nearest hundredth

0.45


So the standard deviation is roughly 0.45




25th and 75th percentiles:

The 25th and 75th percentiles are simply the first and third quartiles. We found these earlier to be 0.3 and 1.2.



So the 25th and 75th percentiles are 0.3 and 1.2


Radicals/198817: One person says that numbers in radicals are useless because they do not have any real world relevance. Give a convincing practical example to show this person that they are very practical and we need them.
1 solutions

Answer 149294 by jim_thompson5910(28595) About Me  on 2009-06-03 13:26:54 (Show Source):
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Let's say that you want to find the distance between two points. You will then use that distance and add it to other distances you find. Also, you want to keep your calculations as exact as possible (to avoid any errors). To keep things exact, you most likely end up with a radical.

For example, let's say that you want to find the distance between the points (1,2) and (5,8):

d=sqrt%28%28x%5B1%5D-x%5B2%5D%29%5E2%2B%28y%5B1%5D-y%5B2%5D%29%5E2%29 Start with the distance formula.


d=sqrt%28%281-5%29%5E2%2B%282-8%29%5E2%29 Plug in x%5B1%5D=1, x%5B2%5D=5, y%5B1%5D=2, and y%5B2%5D=8.


d=sqrt%28%28-4%29%5E2%2B%282-8%29%5E2%29 Subtract 5 from 1 to get -4.


d=sqrt%28%28-4%29%5E2%2B%28-6%29%5E2%29 Subtract 8 from 2 to get -6.


d=sqrt%2816%2B%28-6%29%5E2%29 Square -4 to get 16.


d=sqrt%2816%2B36%29 Square -6 to get 36.


d=sqrt%2852%29 Add 16 to 36 to get 52.


d=2%2Asqrt%2813%29 Simplify the square root.


Now if you found other distances (in terms of radicals), you could add them to this given distance and keep things exact. Once you are done with all of your calculations, you can use a calculator to find the approximate value.


Proofs/198757: This question is from textbook a survey of mathematics with apllications
3. Write the following compound statement in symbolic form
Let p: Today is Friday.
q: Tomorrow is not the day to go shopping.
If tomorrow is not the day to go shopping, then today is not Friday.

4. Construct a truth table for ~ (p Ù q)


5. Write the converse, inverse, and contrapositive of the following conditional statement
If the sun is shining, then it will not rain.

1 solutions

Answer 149261 by jim_thompson5910(28595) About Me  on 2009-06-02 20:32:28 (Show Source):
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# 3

"If tomorrow is not the day to go shopping, then today is not Friday" translates into the symbolic argument: q -> ~p

Recall, ~p means NOT p and -> means "if..then.."

# 4
What is the symbol "Ù". Is this a typo?

# 5

Original Statement: If the sun is shining, then it will not rain.
Converse: If it will not rain, then the sun is shining
Inverse: If the sun is not shining, then it will rain
Contrapositive: If it will rain, then the sun is not shining


Distributive-associative-commutative-properties/198758: multiply this polynoimials
?

(3x + 4) (5x - 9)

1 solutions

Answer 149260 by jim_thompson5910(28595) About Me  on 2009-06-02 20:29:01 (Show Source):
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%283x%2B4%29%285x-9%29 Start with the given expression.


Now let's FOIL the expression.


Remember, when you FOIL an expression, you follow this procedure:


%28highlight%283x%29%2B4%29%28highlight%285x%29-9%29 Multiply the First terms:%283%2Ax%29%2A%285%2Ax%29=15%2Ax%5E2.


%28highlight%283x%29%2B4%29%285x%2Bhighlight%28-9%29%29 Multiply the Outer terms:%283%2Ax%29%2A%28-9%29=-27%2Ax.


%283x%2Bhighlight%284%29%29%28highlight%285x%29-9%29 Multiply the Inner terms:%284%29%2A%285%2Ax%29=20%2Ax.


%283x%2Bhighlight%284%29%29%285x%2Bhighlight%28-9%29%29 Multiply the Last terms:%284%29%2A%28-9%29=-36.


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So we have the terms: 15%2Ax%5E2, -27%2Ax, 20%2Ax, and -36


15%2Ax%5E2-27%2Ax%2B20%2Ax-36 Now add every term listed above to make a single expression.


15%2Ax%5E2-7%2Ax-36 Now combine like terms.


So %283x%2B4%29%285x-9%29 FOILs to 15%2Ax%5E2-7%2Ax-36.


In other words, %283x%2B4%29%285x-9%29=15%2Ax%5E2-7%2Ax-36.


Exponents-negative-and-fractional/198756: Can you please help me simplify 3a%5E-2 and %28x%5E2y%5E-3%29%5E2 please i really need help i have a test tomarrow and i still don't understand this stuff.
1 solutions

Answer 149259 by jim_thompson5910(28595) About Me  on 2009-06-02 20:27:56 (Show Source):
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Recall that x%5E%28-2%29=1%2Fx%5E2. If you have a negative exponent, then you simply flip the fraction to make it positive.

So 3a%5E%28-2%29=3%281%2Fa%5E2%29=3%2Fa%5E2


which means that 3a%5E%28-2%29=3%2Fa%5E2


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Also, we'll use the identity %28x%5Ey%29%5Ez=x%5E%28y%2Az%29


%28x%5E2y%5E%28-3%29%29%5E2 Start with the given expression.


x%5E%282%2A2%29y%5E%28%28-3%29%2A%282%29%29 Use the identity given above to multiply the outer exponent with EVERY exponent inside the parenthesis.


x%5E%284%29y%5E%28-6%29 Multiply


x%5E%284%29%281%2Fy%5E6%29 Now flip the fraction to make the exponent positive


x%5E4%2Fy%5E6 Multiply


So %28x%5E2y%5E%28-3%29%29%5E2=x%5E4%2Fy%5E6


Expressions-with-variables/198753: Translate as an algebric expression:
The product of 35% and some number. Type the percentage as a decimal. Use b to represent some number.
Answer: .35b. Could you please let me know if this is correct.
Thanks
1 solutions

Answer 149258 by jim_thompson5910(28595) About Me  on 2009-06-02 20:23:32 (Show Source):
You can put this solution on YOUR website!
You are correct. Good job.

You can check it by letting "b" be some easy number to deal with like 100. So 0.35*100=35. Since 35% of a 100 is 35, this verifies the expression.


test/198754: This question is from textbook Intro & Inter Algebra
Sorry I forgot to include the problem:
APPENDEX D 485/32 Section 8.1 at the back of the book.
Find an equation of each line. Write the equation using function notation.
Through (-4,8); perpendicular to 2x – 3y=1
1 solutions

Answer 149256 by jim_thompson5910(28595) About Me  on 2009-06-02 20:21:46 (Show Source):
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2x-3y=1 Start with the given equation.


-3y=1-2x Subtract 2x from both sides.


-3y=-2x%2B1 Rearrange the terms.


y=%28-2x%2B1%29%2F%28-3%29 Divide both sides by -3 to isolate y.


y=%28%28-2%29%2F%28-3%29%29x%2B%281%29%2F%28-3%29 Break up the fraction.


y=%282%2F3%29x-1%2F3 Reduce.


We can see that the equation y=%282%2F3%29x-1%2F3 has a slope m=2%2F3 and a y-intercept b=-1%2F3.


Now to find the slope of the perpendicular line, simply flip the slope m=2%2F3 to get m=3%2F2. Now change the sign to get m=-3%2F2. So the perpendicular slope is m=-3%2F2.


Now let's use the point slope formula to find the equation of the perpendicular line by plugging in the slope m=2%2F3 and the coordinates of the given point .


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


y-8=%28-3%2F2%29%28x--4%29 Plug in m=-3%2F2, x%5B1%5D=-4, and y%5B1%5D=8


y-8=%28-3%2F2%29%28x%2B4%29 Rewrite x--4 as x%2B4


y-8=%28-3%2F2%29x%2B%28-3%2F2%29%284%29 Distribute


y-8=%28-3%2F2%29x-6 Multiply


y=%28-3%2F2%29x-6%2B8 Add 8 to both sides.


y=%28-3%2F2%29x%2B2 Combine like terms.


So the equation of the line perpendicular to 2x-3y=1 that goes through the point is y=%28-3%2F2%29x%2B2.


The equation in function notation would then be f%28x%29=%28-3%2F2%29x%2B2


Here's a graph to visually verify our answer:
Graph of the original equation y=%282%2F3%29x-1%2F3 (red) and the perpendicular line y=%28-3%2F2%29x%2B2 (green) through the point .