Question

Solve each system by elimination
-3x-9y=-9
3x-3y=-3

Answer 1

`x = 0\\\\y = 1`

Explanation:

We have the equations

`-3x - 9y = - 9`

`3x - 3y = - 3`

Add the equations

`\begin{aligned}3x-3y& =-3\\+\\\underline{-3x-9y&=-9}\\-12y&=-12\\\end{aligned}\\\\\\y = (-12)/(-12) = 1\\\\`

Substitute y = 1 in the first equation:

`-3x - 9 \cdot 1 = -9\\ \\-3x - 9 = -9\\\\-3x = -9 + 9 \text{ (add -9 to both sides)}\\\\-3x = 0\\\\x = 0\\`