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Graphs/122215: Graph the function for each.
7. f (x) = -2x – 5
1 solutions
Answer 89708 by jim_thompson5910(28715) on 2008-01-23 23:23:59 (Show Source):
You can put this solution on YOUR website!
Looking at  we can see that the equation is in slope-intercept form  where the slope is  and the y-intercept is
Since  this tells us that the y-intercept is ) .Remember the y-intercept is the point where the graph intersects with the y-axis
So we have one point
Now since the slope is comprised of the "rise" over the "run" this means
Also, because the slope is  , this means:
which shows us that the rise is -2 and the run is 1. This means that to go from point to point, we can go down 2 and over 1
So starting at ) , go down 2 units
and to the right 1 unit to get to the next point
Now draw a line through these points to graph
 So this is the graph of  through the points ) and
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Graphs/122213: Evaluate each function for the value specified.
5. f (x) = x2 - 7x + 10;
find (a) f (0), (b) f (5), and (c) f (-2).
1 solutions
Answer 89706 by jim_thompson5910(28715) on 2008-01-23 23:20:12 (Show Source):
You can put this solution on YOUR website!a)
Let's evaluate
 Start with the given function.
 Plug in  . In other words, replace each x with 0.
 Evaluate  to get 0.
 Multiply -7 and 0 to get 0
 Now combine like terms
b)
Let's evaluate
 Start with the given function.
 Plug in  . In other words, replace each x with 5.
 Evaluate  to get 25.
 Multiply -7 and 5 to get -35
 Now combine like terms
c)
Let's evaluate
 Start with the given function.
 Plug in  . In other words, replace each x with -2.
 Evaluate  to get 4.
 Multiply -7 and -2 to get 14
 Now combine like terms
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Graphs/122212: 4. Number problems. You have at least $30 in change in your drawer, consisting of dimes and quarters. Write an inequality that shows the different number of coins in your drawer. 1 solutions
Answer 89705 by jim_thompson5910(28715) on 2008-01-23 23:17:35 (Show Source):
You can put this solution on YOUR website!Let d=# of dimes, q=# of quarters, s=sum of your money
Since a dime is 10 cents, it is $0.10 by conversion from cents to dollars. Also a quarter, which is 25 cents, is $0.25
So the sum of your money would be
Since you have at least $30, this means that the sum of your money is greater than $30 like this:
 Now plug in
Answer:
So the inequality that represents this problem is
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Graphs/122210: Graph each of the following inequalities.
3. 3x – 4y > 12
1 solutions
Answer 89703 by jim_thompson5910(28715) on 2008-01-23 23:09:13 (Show Source):
You can put this solution on YOUR website!In order to graph  , we need to graph the equation  (just replace the inequality sign with an equal sign).
So lets graph the line  (note: if you need help with graphing, check out this solver)
graph of
Now lets pick a test point, say (0,0). Any point will work, (just make sure the point doesn't lie on the line) but this point is the easiest to work with. Now evaluate the inequality with the test point
Substitute (0,0) into the inequality
Plug in and
Simplify
(note: for some reason, some of the following images do not display correctly in Internet Explorer. So I recommend the use of Firefox to see these images.)
Since this inequality is not true, we do not shade the entire region that contains (0,0). So this means we shade the region that is on the opposite side of the line
 Graph of  with the boundary (which is the line  in red) and the shaded region (in green)
(note: since the inequality contains a greater-than sign, this means the boundary is excluded. This means the solid red line is really a dashed line)
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Graphs/122208: We have graphed the boundary line for the linear inequality. Determine the correct half – plane in each case, and complete the graph.
y>3 1 solutions
Answer 89701 by jim_thompson5910(28715) on 2008-01-23 23:03:41 (Show Source):
You can put this solution on YOUR website!Start with the graph of
 graph of
Now lets pick a test point, say (0,0). Any point will work, (just make sure the point doesn't lie on the line) but this point is the easiest to work with. Now evaluate the inequality  with the test point
Substitute (0,0) into the inequality
 Plug in  and
 Simplify
(note: for some reason, some of the following images do not display correctly in Internet Explorer. So I recommend the use of Firefox to see these images.)
Since this inequality is not true, we do not shade the entire region that contains (0,0). So this means we shade the region that is on the opposite side of the line
 Graph of  with the boundary (which is the line  in red) and the shaded region (in green)
(note: since the inequality contains a greater-than sign, this means the boundary is excluded. This means the solid red line is really a dashed line)
So the correct half-plane is above the line
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Graphs/122153: I am stuck on this linear equation. I also need to find the rise over run too. This is what I have so far.
2x + 4y + 1 = 0
4y = 2x - 1
/4 /4 /4
y = 2/4x -1/4
y = 1/2x -1/4
1 solutions
Answer 89673 by jim_thompson5910(28715) on 2008-01-23 19:48:28 (Show Source):
You can put this solution on YOUR website!You made a mistake in converting to slope-intercept form
"4y = 2x - 1" <--- In this step, it should be -2x since you subtract 2x from both sides
So the equation in slope-intercept form is
Looking at  we can see that the equation is in slope-intercept form  where the slope is  and the y-intercept is
Since  this tells us that the y-intercept is ) .Remember the y-intercept is the point where the graph intersects with the y-axis
So we have one point
Now since the slope is comprised of the "rise" over the "run" this means
Also, because the slope is  , this means:
which shows us that the rise is -1 and the run is 2. This means that to go from point to point, we can go down 1 and over 2
So starting at ) , go down 1 unit
and to the right 2 units to get to the next point
Now draw a line through these points to graph
 So this is the graph of  through the points ) and
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Expressions-with-variables/122150: I think this is the right section. My father in law is trying to help someone with their homework and called me. My algebra memory has faded :)
solve for x
x=zb-zk^2 (or, in english, x equals zb minus zk squared) 1 solutions
Answer 89669 by jim_thompson5910(28715) on 2008-01-23 19:30:54 (Show Source):
You can put this solution on YOUR website!Since x is alone on the left side it is already isolated and solved for. So no work needs to be done if you want to solve for x. Do you want to solve for another variable?
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Graphs/122142: solve the following systems by using either addition or substitution. if a unique solution does not exist, state whether the system is dependent of inconsistent.
10x+2y=7
y=-5x+3 1 solutions
Answer 89666 by jim_thompson5910(28715) on 2008-01-23 19:13:05 (Show Source):
You can put this solution on YOUR website!Start with the given system
 Plug in  into the first equation. In other words, replace each  with  . Notice we've eliminated the  variables. So we now have a simple equation with one unknown.
 Distribute
 Combine like terms on the left side
 Subtract 6 from both sides
 Combine like terms on the right side
Since this equation is never true for any x value, this means there are no solutions. So the system is inconsistent.
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Number-Line/122135: The problem is this:
-5 is greater than/equal to x-6 1 solutions
Answer 89661 by jim_thompson5910(28715) on 2008-01-23 18:53:01 (Show Source):
You can put this solution on YOUR website!
 Start with the given inequality
 Add 5 to both sides
 Subtract x from both sides
 Combine like terms on the right side
 Divide both sides by -1 to isolate x (note: Remember, dividing both sides by a negative number flips the inequality sign)
 Divide
--------------------------------------------------------------
Answer:
So our answer is
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Trigonometry-basics/122078: #10
Find the coordinates [r, theta] of all points of intersection:
r = 2sin(theta) and r = 1
a) [½, pi/3] and [½, 5pi/3]
b) [½, pi/6] and [½, 5pi/6]
c) [1, pi/3] and [1, 5pi/3]
d) [1, pi/6] and [1, 5pi/6]
e) None of these
1 solutions
Answer 89607 by jim_thompson5910(28715) on 2008-01-23 14:29:00 (Show Source):
You can put this solution on YOUR website!Start with the given set of equations
) Plug in  into the first equation
) Divide both sides by 2
=\theta) Take the arcsine of both sides to isolate
 or  Take the arcsine of  to get  and  :
So because the answer format is ) this means we have the solutions:
) and
So the answer is D)
Note: Since the second equation is  , this means that the first coordinate (which is r) is also 1. So the answers will look like (1,?) and (1,?). So if you had no idea what to do, you could easily eliminate possible answers a) and b)
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Quadratic-relations-and-conic-sections/122072: #9
Identify x = 4sint
y = 5cost
a) circle
b) parabola
c) ellipse
d) hyperbola
e) none of these
1 solutions
Answer 89606 by jim_thompson5910(28715) on 2008-01-23 14:10:01 (Show Source):
You can put this solution on YOUR website! Start with the first parametric equation
 Divide both sides by 4 to isolate  .
 Start with the second parametric equation
 Divide both sides by 5 to isolate  .
Now we're going to use the trig identity:
 Replace  with  . Replace  with  . This is why we isolated sine and cosine.
 Square  to get  . Square  to get  .
Notice how the equation is now in the form  (note: h and k are equal to zero in this case)
So this shows us that  graphs an ellipse (since the above equation is the general equation of an ellipse).
So this means that the two parametric equations also graph an ellipse. So the answer is C)
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Complex_Numbers/122065: Find (1 / sq. rt. 2 + i / sq. rt. 2) ^ 8
a.) -8
b.) 256
c.) 8
d.) 1
e.) None of these
1 solutions
Answer 89603 by jim_thompson5910(28715) on 2008-01-23 13:50:16 (Show Source):
You can put this solution on YOUR website! Start with the given expression
It's very useful to note that  and  . So the expression is equivalent to
Now we're going to use De Moivre's theorem to solve this problem.
Remember, De Moivre's theorem states:
So using De Moivre's theorem we get
 Multiply  and  to get  . Now reduce to get
 Take the cosine of  to get 1. Take the sine of  to get 0.
 Remove the zero term
So  simplifies to 1.
In other words,
So the answer is D)
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Linear-equations/122018: Find the equation of the line through the two points (5,3) and (-7,7).
1 solutions
Answer 89574 by jim_thompson5910(28715) on 2008-01-23 10:34:54 (Show Source):
You can put this solution on YOUR website!First lets find the slope through the points (  ,  ) and (  ,  )
 Start with the slope formula (note: ) is the first point (  ,  ) and ) is the second point (  ,  ))
 Plug in  ,  ,  ,  (these are the coordinates of given points)
 Subtract the terms in the numerator  to get  . Subtract the terms in the denominator  to get
 Reduce
So the slope is
------------------------------------------------
Now let's use the point-slope formula to find the equation of the line:
------Point-Slope Formula------
 where  is the slope, and ) is one of the given points
So lets use the Point-Slope Formula to find the equation of the line
 Plug in  ,  , and  (these values are given)
 Distribute
 Multiply  and  to get
 Add  to both sides to isolate y
 Combine like terms  and  to get  (note: if you need help with combining fractions, check out this solver)
------------------------------------------------------------------------------------------------------------
Answer:
So the equation of the line which goes through the points (  ,  ) and (  ,  ) is:
The equation is now in  form (which is slope-intercept form) where the slope is  and the y-intercept is
Notice if we graph the equation  and plot the points (  ,  ) and (  ,  ), we get this: (note: if you need help with graphing, check out this solver)
Graph of through the points ( , ) and ( , )
Notice how the two points lie on the line. This graphically verifies our answer.
|
Pythagorean-theorem/121959: 1. A customer wants to make a teepee in his backyard for his children. He plans to use lengths of PVC plumbing pipe for the supports on the teepee, and he wants the teepee to be 12 feet across and 8 feet tall. How long should the PVC plumbing pipe be? 1 solutions
Answer 89539 by jim_thompson5910(28715) on 2008-01-23 00:32:37 (Show Source):
You can put this solution on YOUR website!If we cut the triangle in half vertically down the middle, we get this triangle:
Since we can see that the triangle has legs of 8 and 6 with a hypotenuse of x, we can use Pythagoreans theorem to find the unknown side.
Pythagoreans theorem:
 where a and b are the legs of the triangle and c is the hypotenuse
 Plug in a=8, b=6, and c=x. Now lets solve for x
 Square each individual term
 Combine like terms
 Take the square root of both sides
 Simplify the square root
So the hypotenuse of this triangle is 10
Since we cut the triangle in half, this means the other triangle's hypotenuse also has a length of 10
After putting the two triangles back together, we have this triangle:
Since the figure was pointing to one side, I'm assuming that the problem is asking about one side. So the length of one pipe is 10 ft.
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Trigonometry-basics/121956: 7) For x E [0,2pi), solve: cos2x = cosx
a) 2 pi/3, 4pi/3 and pi
b) 2 pi/3, 4 pi/3 and 0
c) Pi/3, 5pi/3 and 0
d) Pi/6, 5pi/6 and pi
e) 5pi/6, 7pi/6 and pi 1 solutions
Answer 89537 by jim_thompson5910(28715) on 2008-01-23 00:08:41 (Show Source):
You can put this solution on YOUR website!=\cos\left(x\right)) Start with the given equation
-1=\cos\left(x\right)) Replace ) with -1) . Note: I'm using the identity
-1-\cos\left(x\right)=0) Subtract  from both sides
-\cos\left(x\right)-1=0) Rearrange the terms
Now let
 Replace each  with
 Factor the left side
Now set each factor equal to zero
 or
Now solve for u in each case
 or
Now remember we let  . So this means
 or
So let's solve  to get  or  . However, since  is excluded the only solution for  is
Now let's solve  to get  or
So putting these solutions together, we get:
 ,  or
So this means the answer is B)
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Trigonometry-basics/121955: 6) find csc(arctan 8/15)
a) 17/8
b) 8/17
c) 15/17
d) 17/15
e) Undefined 1 solutions
Answer 89535 by jim_thompson5910(28715) on 2008-01-23 00:01:59 (Show Source):
You can put this solution on YOUR website!First a triangle with legs of 8 and 15. Let x be the angle we'll refer to.
By using pythagorean's theorem, we find that the hypotenuse is 17 units
Since  this means  (notice how the arctangent is gives you an angle)
Now remember  and  (remember the cosecant and sine function are reciprocals of each other)
So
which also means
So the answer is A)
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Trigonometry-basics/121954: 5) Find the period of f(x) = 3 - 2cos(3x+pi)
a) 2 pi / 3
b) Pi / 3
c) Pi / 6
d) Pi
e) 2 pi 1 solutions
Answer 89533 by jim_thompson5910(28715) on 2008-01-22 23:55:31 (Show Source):
You can put this solution on YOUR website!
The general form of cosine is:
where the period
So for the trig function  which also looks like  . Notice how  matches up with  , so  which means
 Now simply plug in  into the period formula
So the period is
So the answer is A)
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Quadratic-relations-and-conic-sections/121913: Name the vertex for the parabol with equation
y= 3x^2-12x+16 1 solutions
Answer 89531 by jim_thompson5910(28715) on 2008-01-22 23:50:55 (Show Source):
You can put this solution on YOUR website!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:
From the equation  we can see that a=3 and b=-12
 Plug in b=-12 and a=3
 Negate -12 to get 12
 Multiply 2 and 3 to get 6
 Reduce
So the axis of symmetry is
So the x-coordinate of the vertex is  . Lets plug this into the equation to find the y-coordinate of the vertex.
 Start with the given polynomial
 Plug in
 Raise 2 to the second power to get 4
 Multiply 3 by 4 to get 12
 Multiply 12 by 2 to get 24
 Now combine like terms
So the vertex is (2,4)
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Graphs/121930: solve the following systems by addition. If a unique solution does not exist, state whether the system is inconsistent or dependent.
2x+3y=1
5x+3y=16 1 solutions
Answer 89525 by jim_thompson5910(28715) on 2008-01-22 23:44:08 (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 2 and 5 to some equal number, we could try to get them to the LCM.
Since the LCM of 2 and 5 is 10, we need to multiply both sides of the top equation by 5 and multiply both sides of the bottom equation by -2 like this:
Multiply the top equation (both sides) by 5
Multiply the bottom equation (both sides) by -2
So after multiplying we get this:


Notice how 10 and -10 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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Pythagorean-theorem/121931: A 15 feet ladder is 5 feet away from a wall. How far above the floor is the top of the ladder? 1 solutions
Answer 89524 by jim_thompson5910(28715) on 2008-01-22 23:43:20 (Show Source):
You can put this solution on YOUR website!We basically have this triangle set up:
Since we can see that the triangle has legs of x and 5 with a hypotenuse of 15, we can use Pythagoreans theorem to find the unknown side.
Pythagoreans theorem:
 where a and b are the legs of the triangle and c is the hypotenuse
 Plug in a=x, b=5, and c=15. Now lets solve for x
 Square each individual term
 Subtract 25 from both sides
 Combine like terms
 Take the square root of both sides
 Simplify the square root
Which approximates to...
So our answer is
So the top of the ladder is about 14.14 feet about the floor
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Linear-systems/121939: I need help with the following problems:
y = 2x + 6
y = -x -3
y - 3x = 9
2y + x = 4
y + 4 = 2x
6x - 3y = 12
1 solutions
Answer 89522 by jim_thompson5910(28715) on 2008-01-22 23:40:57 (Show Source):
You can put this solution on YOUR website!#1
Start with the given system
 Plug in  into the first equation. In other words, replace each  with  . Notice we've eliminated the  variables. So we now have a simple equation with one unknown.
 Distribute
 Combine like terms on the left side
 Add 3 to both sides
 Subtract 2x from both sides
 Combine like terms on the left side
 Combine like terms on the right side
 Divide both sides by -3 to isolate x
 Divide
Now that we know that  , we can plug this into  to find
 Substitute  for each
 Simplify
So our answer is  and  which also looks like
Notice if we graph the two equations, we can see that their intersection is at ) . So this verifies our answer.
 Graph of  (red) and  (green)
#2
| 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
Add to both sides
Divide both sides by 1.
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 2 to 
Multiply
Reduce any fractions
Subtract from both sides
Combine the terms on the right side
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
Add to both sides
Combine the terms on the right side
Multiply both sides by . This will cancel out 2 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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#3
 Start with the first equation
 Solve for y by subtracting 4 from both sides
Start with the given system
 Plug in  into the first equation. In other words, replace each  with  . Notice we've eliminated the  variables. So we now have a simple equation with one unknown.
 Distribute
 Combine like terms on the left side
 Subtract 12 from both sides
 Combine like terms on the right side
 Simplify
Since this equation is always true for any x value, this means x can equal any number. So there are an infinite number of solutions.
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Graphs/121953: This question is from textbook
x+5/2=6 1 solutions
Answer 89518 by jim_thompson5910(28715) on 2008-01-22 23:35:47 (Show Source):
You can put this solution on YOUR website!
 Start with the given equation
 Multiply both sides by the LCM of 2. This will eliminate the fractions (note: if you need help with finding the LCM, check out this solver)
 Distribute and multiply the LCM to each side
 Subtract 5 from both sides
 Combine like terms on the right side
 Divide both sides by 2 to isolate x
--------------------------------------------------------------
Answer:
So our answer is  (which is approximately  in decimal form)
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Quadratic_Equations/121936: SOLVE BY SUBSTITUTION
5X-2Y=-5
Y-5X=3 1 solutions
Answer 89516 by jim_thompson5910(28715) on 2008-01-22 23:34:55 (Show Source):
You can put this solution on YOUR website!
| 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 -2.
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 1 to 
Multiply
Reduce any fractions
Subtract from both sides
Make 3 into a fraction with a denominator of 2
Combine the terms on the right side
Make -5 into a fraction with a denominator of 2
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 1 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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