Question

Solve by adding or subtracting.
x+y=-10
2x-y=-8

Answer 1

(-6,-4)

Explanation:

I'm going to solve this system by elimination. You can only do this when both equations have the same form; here it is ax+by=c. What that means is a variable gets eliminated after adding or subtracting the equations.

This elimination can be applied to this system by adding the equations. This will elimination the y part because they are opposites.

x+y=-10

2x-y=-8

-‐---------- Adding.

3x+0=-18

3x=-18

Divide both sides by 3:

x=-18/3

x=-6

Using one of the equations we started with along with x=-6, we can find y.

x+y=-10 with x=-6

-6+y=-10

Add 6 on both sides:

y=-4

The solution is (x,y)=(-6 -4).

Answer 2

`x=-6\\y=-4`

Explanation:

To solve, isolate your first equation for y.

`x+y=-10\\y=-x-10`

Now, plug in this y value to your second equation.

`2x-(-x-10)=-8\\2x+x+10=-8\\3x+10=-8\\3x=-18\\x=-6`

Now, plug your x value into your first equation and solve for y.

`-6+y=-10\\y=-4`