solve each system by substitution

Question

2x-3y=-13 y=2x+7

Answer 1

 

               2x  -3y  =  -13                 y=2x  +7

 

              2x  -3(2x +7) = -13          y= 2(-2) + 7

 

              2x -6x  -21  = -13             y=  -4 +7

 

             -4x  -21  = -13                    y =3

 

                    +21     +21

              _______________

 

                -4x      = 8

               ____       __

                 -4          -4

 

                X  =  -2                                                                                                               

 

 

                        Hope this helps!

 

Answer 2

2x - 3y = -13

 

y = 2x + 7

 

Substitute 2x + 7 for y in the first equation:

 

2x - 3(2x + 7) = -13

 

2x - 6x - 21 = -13

 

-4x - 21 = -13

 

-4x = -13 + 21 = 8

 

x = 8/-4 = -2.

 

Find y but plugging x = -2 into y = 2x + 7:

 

y = 2(-2) + 7 = -4 + 7 = 3.

 

The solution is x = -2, y = 3. This is usually written as the ordered pair (-2, 3).