Question

How do i solve -2x-2y=-6 and x-2y=15 using the elimination method

Answer 1

Subtract the corresponding sides of one equation from the other:


`\begin{cases}-2x-2y=-6\\x-2y=15\end{cases}`

`\implies (-2x-2y)-(x-2y)=-6-15`

`\implies -3x+0y=-21`

`\implies x=7`

Now plug this into either equation to find
`y`.


`x-2y=15\implies 7-2y=15`

`\implies-2y=8`

`\implies y=-4`