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solve the problem using substitution.

x-2y=-2

3x-2y=2

cesix  Oct 25, 2017

Best Answer 

 #1
avatar+7096 
+2

This is a little bit different from the normal way of substituting, but it is still substution!

 

x - 2y  =  -2

3x - 2y  =  2

 

(x - 2y) - (3x - 2y)  =  (x - 2y) - (3x - 2y)

                                                              Since  x - 2y = -2 , we can substitute  -2  in for  x - 2y .

(x - 2y) - (3x - 2y)  =  (-2) - (3x - 2y)

                                                              Since  3x - 2y = 2 , we can substitute  2  in for  3x - 2y .

(x - 2y) - (3x - 2y)  =  (-2) - (2)

                                                   Distribute the  -1 .

x - 2y - 3x + 2y  =  -2 - 2

                                                   Combine like terms.

-2x  =  -4

                                                   Divide both sides by  -2 .

x  =  2

 

Now we know what  x  is. Let's plug this value into the first equation to find  y .

 

2 - 2y  =  -2

                      Subtract  2  from both sides.

-2y  =  -4

                      Divide both sides by  -2 .

y  =  2

hectictar  Oct 25, 2017
 #1
avatar+7096 
+2
Best Answer

This is a little bit different from the normal way of substituting, but it is still substution!

 

x - 2y  =  -2

3x - 2y  =  2

 

(x - 2y) - (3x - 2y)  =  (x - 2y) - (3x - 2y)

                                                              Since  x - 2y = -2 , we can substitute  -2  in for  x - 2y .

(x - 2y) - (3x - 2y)  =  (-2) - (3x - 2y)

                                                              Since  3x - 2y = 2 , we can substitute  2  in for  3x - 2y .

(x - 2y) - (3x - 2y)  =  (-2) - (2)

                                                   Distribute the  -1 .

x - 2y - 3x + 2y  =  -2 - 2

                                                   Combine like terms.

-2x  =  -4

                                                   Divide both sides by  -2 .

x  =  2

 

Now we know what  x  is. Let's plug this value into the first equation to find  y .

 

2 - 2y  =  -2

                      Subtract  2  from both sides.

-2y  =  -4

                      Divide both sides by  -2 .

y  =  2

hectictar  Oct 25, 2017
 #2
avatar+12 
0

solve the systems of equations:

 

3x+y=20
2x+3y=18     (no graph)

cesix  Oct 25, 2017

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