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Linear-equations/656140: solving by elimination
5x-7y=-49
3x+9y=-3 1 solutions
Answer 409358 by MathLover1(6625) on 2012-09-24 10:02:31 (Show Source):
You can put this solution on YOUR website!
| Solved by pluggable solver: Solving a System of Linear Equations by Elimination/Addition |
Lets start with the given system of linear equations


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 but have opposite signs (for instance 2 and -2 are equal but have opposite signs). This way they will add to zero.
So to make the x coefficients equal but opposite, we need to multiply both x coefficients by some number to get them to an equal number. So if we wanted to get 5 and 3 to some equal number, we could try to get them to the LCM.
Since the LCM of 5 and 3 is 15, we need to multiply both sides of the top equation by 3 and multiply both sides of the bottom equation by -5 like this:
Multiply the top equation (both sides) by 3
Multiply the bottom equation (both sides) by -5
So after multiplying we get this:


Notice how 15 and -15 add to zero (ie )
Now add the equations together. In order to add 2 equations, group like terms and combine them


Notice the x coefficients add to zero and cancel out. This means we've eliminated x altogether.
So after adding and canceling out the x terms we're left with:

Divide both sides by to solve for y
Reduce
Now plug this answer into the top equation to solve for x
Plug in 
Multiply
Subtract from both sides
Combine the terms on the right side
Multiply both sides by . This will cancel out on the left side.
Multiply the terms on the right side
So our answer is
, 
which also looks like
( , )
Notice if we graph the equations (if you need help with graphing, check out this solver)


we get
graph of (red) (green) (hint: you may have to solve for y to graph these) and the intersection of the lines (blue circle).
and we can see that the two equations intersect at ( , ). This verifies our answer. |
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Graphs/655963: what is the equation of a line passing through (-2, -1) and (6, 3)? 1 solutions
Answer 409315 by MathLover1(6625) on 2012-09-23 20:28:46 (Show Source):
You can put this solution on YOUR website!
| Solved by pluggable solver: FIND EQUATION of straight line given 2 points |
hahaWe are trying to find equation of form y=ax+b, where a is slope, and b is intercept, which passes through points (x1, y1) = (-2, -1) and (x2, y2) = (6, 3).
Slope a is .
Intercept is found from equation , or . From that,
intercept b is , or .
y=(0.5)x + (0)
Your graph:

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expressions/655947: By which property is the equation 1 • 0 • (-1) = 0 true?
A. Identify Property of Multiplication
B. Multiplication Property of Zero
C. Multiplication Property of -1
D. Inverse Property of Addition 1 solutions
Answer 409311 by MathLover1(6625) on 2012-09-23 20:21:13 (Show Source):
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Sequences-and-series/655658: Write a linear function where f(2)=4,f(4)=2 and f(3)=3. 1 solutions
Answer 409227 by MathLover1(6625) on 2012-09-23 12:59:30 (Show Source):
You can put this solution on YOUR website!If  ,  ,  , then the graph of the function contains the point (  ,  ),(  ,  ), and (  ,  ).
Use the two point form of an equation of a straight line and the points (  ,  ),(  ,  ):
 where (x1,y1)and (x2,y2) are the coordinates of the given points.
here is a proof that all three of given points lie on this line
| Solved by pluggable solver: To determine if 3 points lie in a line |
The 3 points lie on a same plane. For all points to lie on a line they should satisfy the equation of a line. Hence any two points taken on a line should calculate to the same slope of a line.
In order to prove the 3 points to lie on a line, as there exists a unique line containing three points and every line has a unique slope.
Hence it will be sufficient to prove that the slope calculated taking 2 points at a time should be equal.
Slope of line taking points (X1,Y1) and (X2,Y2) is

........................(1)
Slope of line taking points (X3,Y3) and (X1,Y1) is

........................(2)
From conditions (1) and (2)
The slopes are equal hence the 3 points can lie on same line.
If the slope calculated from points (X2,Y2) and (X3,Y3) comes out to be same then it is confirmed that the 3 points lie on a same line.

........................(3)
From (1),(2) and (3)
Hence, It is proved that the 3 points lie on same line.
To read more on equations of a line refer to articles on wikipedia
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test/655406: Through :(-4,-4), parallel to x=0 1 solutions
Answer 409112 by MathLover1(6625) on 2012-09-22 18:23:48 (Show Source):
You can put this solution on YOUR website!Slope Intercept form:
 =?
 =?
Find  :
Since you know your line is parallel to  then we know it is a  line on the  that has points of [(0,1), (0,2), etc...]
take points: (0,1) and given point (-4,-4)
 ...
So.... back to
Finally  or
or, you can find it this way: first slope, then equation of line through the given point and slope
| Solved by pluggable solver: FIND a line by slope and one point |
What we know about the line whose equation we are trying to find out:
- it goes through point (-4, -4)
- it has a slope of -0.75
First, let's draw a diagram of the coordinate system with point (-4, -4) plotted with a little blue dot:

Write this down: the formula for the equation, given point and intercept a, is
(see a paragraph below explaining why this formula is correct)
Given that a=-0.75, and , we have the equation of the line:

Explanation: Why did we use formula ? Explanation goes here. We are trying to find equation y=ax+b. The value of slope (a) is already given to us. We need to find b. If a point ( , ) lies on the line, it means that it satisfies the equation of the line. So, our equation holds for ( , ): Here, we know a, , and , and do not know b. It is easy to find out: . So, then, the equation of the line is: .
Here's the graph:

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expressions/655412: 2(x − 3) 2x − 6
Prove, in complete sentences, whether the left expression is equal to the right expression and discuss which property applies. 1 solutions
Answer 409092 by MathLover1(6625) on 2012-09-22 17:30:36 (Show Source):
You can put this solution on YOUR website! ...left expression
 ... right expression
if the left expression is equal to the right expression, then will be
 ...first multiply
 ...both sides of the equation are same, means it is true
consequently, we can say that left expression   to right expression
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Surface-area/655350: PLEASE HELP! The diameter of a circle is (x+2) units. Express the area of the square in the figure as a polynomial
it is a circle with a line going through the middle, and two arrows going opposite directions below that with x+2 in the center.
http://i49.tinypic.com/2w7pyjp.png < This is a picture for a visual
thanks. 1 solutions
Answer 409079 by MathLover1(6625) on 2012-09-22 15:33:14 (Show Source):
You can put this solution on YOUR website!you are given: the diameter of a circle is  units
you need to express the area of the square in the figure as a polynomial
as you know, the area of the square is  where  is the side of the square
if you take a close look at your picture, you will see that  units
so,the area of the square will be:
so, your answer is:
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Surface-area/655352: PLEASE HELP-
Whats the area of the shaded figure? Round your answer to the nearest tenth.
Can anyone show me step by step how to figure this out? 12.5cm is in the inside. 8.4 is at the bottom. THANKS!
http://i46.tinypic.com/2u8koes.png < picture of the problem with multiple choice answers 1 solutions
Answer 409078 by MathLover1(6625) on 2012-09-22 15:22:18 (Show Source):
You can put this solution on YOUR website!if you look closely at shaded area, you will see that that area could be calculated as following:
you have a square inside ellipse with sides  and  , so its
area is:
than you have two half circles with same diameter of  that you should deduct from the area of the square, and these two halves make one full circle with area  where
so, we have
find their difference:
finaly, you have two half circles, one on left and one on right side of the square, that make one full circle...its diameter is  ; so, its radius is  and the area will be
now, your shaded area will be:
 ...round to one decimal place
so, your answer is
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Linear-systems/655283: I need help on understanding how to solve this problem using substitution and elimination. Please show me how:
4x+5y=13
4x+3y=9
1 solutions
Answer 409026 by MathLover1(6625) on 2012-09-22 09:51:21 (Show Source):
You can put this solution on YOUR website!
solving linear system by substitution:
| Solved by pluggable solver: Solving a linear system of equations by subsitution |
Lets start with the given system of linear equations


Now in order to solve this system by using substitution, we need to solve (or isolate) one variable. I'm going to choose y.
Solve for y for the first equation
Subtract from both sides
Divide both sides by 5.
Which breaks down and reduces to
Now we've fully isolated y
Since y equals we can substitute the expression into y of the 2nd equation. This will eliminate y so we can solve for x.
Replace y with . Since this eliminates y, we can now solve for x.
Distribute 3 to 
Multiply
Reduce any fractions
Subtract from both sides
Make 9 into a fraction with a denominator of 5
Combine the terms on the right side
Make 4 into a fraction with a denominator of 5
Now combine the terms on the left side.
Multiply both sides by . This will cancel out and isolate x
So when we multiply and (and simplify) we get
<---------------------------------One answer
Now that we know that , lets substitute that in for x to solve for y
Plug in into the 2nd equation
Multiply
Subtract from both sides
Combine the terms on the right side
Multiply both sides by . This will cancel out 3 on the left side.
Multiply the terms on the right side
Reduce
So this is the other answer
<---------------------------------Other answer
So our solution is
and 
which can also look like
( , )
Notice if we graph the equations (if you need help with graphing, check out this solver)


we get
graph of (red) and (green) (hint: you may have to solve for y to graph these) intersecting at the blue circle.
and we can see that the two equations intersect at ( , ). This verifies our answer.
-----------------------------------------------------------------------------------------------
Check:
Plug in ( , ) into the system of equations
Let and . Now plug those values into the equation 
Plug in and 
Multiply
Add
Reduce. Since this equation is true the solution works.
So the solution ( , ) satisfies 
Let and . Now plug those values into the equation 
Plug in and 
Multiply
Add
Reduce. Since this equation is true the solution works.
So the solution ( , ) satisfies 
Since the solution ( , ) satisfies the system of equations


this verifies our answer.
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solving linear system by elimination:
| Solved by pluggable solver: Solving a System of Linear Equations by Elimination/Addition |
Lets start with the given system of linear equations


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 but have opposite signs (for instance 2 and -2 are equal but have opposite signs). This way they will add to zero.
So to make the x coefficients equal but opposite, we need to multiply both x coefficients by some number to get them to an equal number. So if we wanted to get 4 and 4 to some equal number, we could try to get them to the LCM.
Since the LCM of 4 and 4 is 4, we need to multiply both sides of the top equation by 1 and multiply both sides of the bottom equation by -1 like this:
Multiply the top equation (both sides) by 1
Multiply the bottom equation (both sides) by -1
So after multiplying we get this:


Notice how 4 and -4 add to zero (ie )
Now add the equations together. In order to add 2 equations, group like terms and combine them


Notice the x coefficients add to zero and cancel out. This means we've eliminated x altogether.
So after adding and canceling out the x terms we're left with:

Divide both sides by to solve for y
Reduce
Now plug this answer into the top equation to solve for x
Plug in 
Multiply
Subtract from both sides
Combine the terms on the right side
Multiply both sides by . This will cancel out on the left side.
Multiply the terms on the right side
So our answer is
, 
which also looks like
( , )
Notice if we graph the equations (if you need help with graphing, check out this solver)


we get
graph of (red) (green) (hint: you may have to solve for y to graph these) and the intersection of the lines (blue circle).
and we can see that the two equations intersect at ( , ). This verifies our answer. |
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Equations/655267: Explain and answer the question
[3a * -7b + b] * [{(sqrt 3)/2}* a^2*b]
note
in the second bracket, you have to find the square root of 3 and then divide in by 2 after that multiply by a square . then multiply by b 1 solutions
Answer 409022 by MathLover1(6625) on 2012-09-22 09:46:43 (Show Source):
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Probability-and-statistics/655216: Construct a scatterplot for the (x, y) values below, and answer the following questions. You needn’t submit your scatterplot with your answer.
x y
1 4
2 6
3 8
4 10
5 11
- Based on the scatterplot, would the correlation between x and y be positive or negative?
- How would you interpret these data in terms of linear regression? Please be sure to see the model in problem 6 of practice items posted in the P&S area
Could you please show work
1 solutions
Answer 408995 by MathLover1(6625) on 2012-09-22 00:03:02 (Show Source):
You can put this solution on YOUR website!
x | y
1 | 4
2 | 6
3 | 8
4 | 10
5 | 11
 .... find the slope
find the equation:
| Solved by pluggable solver: FIND a line by slope and one point |
What we know about the line whose equation we are trying to find out:
- it goes through point (1, 4)
- it has a slope of 3
First, let's draw a diagram of the coordinate system with point (1, 4) plotted with a little blue dot:

Write this down: the formula for the equation, given point and intercept a, is
(see a paragraph below explaining why this formula is correct)
Given that a=3, and , we have the equation of the line:

Explanation: Why did we use formula ? Explanation goes here. We are trying to find equation y=ax+b. The value of slope (a) is already given to us. We need to find b. If a point ( , ) lies on the line, it means that it satisfies the equation of the line. So, our equation holds for ( , ): Here, we know a, , and , and do not know b. It is easy to find out: . So, then, the equation of the line is: .
Here's the graph:

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Correlation:  since as x rises, y rises
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Functions/655172: f(x)= 4|x-4|
Increasing? Decreasing? Constant? On? 1 solutions
Answer 408971 by MathLover1(6625) on 2012-09-21 21:53:04 (Show Source):
You can put this solution on YOUR website!
assuming  is real:
global minimum: min{.  .} is at
Increasing? Decreasing? Constant? On?
(  ,  ]
Thus function is decreasing on this interval in its domain.
[  ,  )
Thus function is increasing on this interval in its domain.
The function is continuous on its entire domain (  ,  )
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Volume/655154: Find the outside surface area. Note that the container may not have a top. Assume a = 4 in., b = 5 in
http://www.webassign.net/smithnm11/9-3-041combo_6alt.gif 1 solutions
Answer 408964 by MathLover1(6625) on 2012-09-21 20:00:42 (Show Source):
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