Question

Solve the system of equations x+y=-8 and -9x-6y=60 by combining the equations

Answer 1

Answer:

x = - 4    y = - 4

Step-by-step explanation:

x+y= - 8

-9x-6y=60

First, solve for x in the first equation:

x+y = - 8       Subtract y from both sides

x + y - y = -8 - y    y cancels on the left

x = - 8 - y

Now plug in what you found for x into the 2nd equation and solve for y.

- 9x - 6y = 60

-9(- 8 - y) - 6y = 60   Multiply out

72 + 9y - 6y = 60

72 + 3y = 60  Subtract 72 from both sides

72 - 72 + 3y = 60 - 72    72 cancels on the left

3y = - 12     Divie both sides by 3

3y/3 = -12/3     3 cancels on the left because 3/3 = 1

y = -4

Now plug your answer for y back into the first equation to get x.

x + y = -8

x + (-4) = - 8  Add 4 to each side

x - 4 + 4 = - 8 + 4   4 cancels on the left

x = -4

x = - 4 and y = - 4