Question

Find the solution of this system of equations2x+7y=-31-4x-4y=-8

Answer 1

To find the solutions, we multiply the first equation by 2, then we sum the equations to solve for y.

`\begin{gathered} \begin{cases}4x+14y=-62 \\ -4x-4y=-8\end{cases}\rightarrow10y=-70 \\ y=-(70)/(10) \\ y=-7 \end{gathered}`

Then, we use y = -7 to find x

`\begin{gathered} 2x+7y=-31 \\ 2x+7(-7)=-31 \\ 2x-49=-31 \\ 2x=-31+49 \\ 2x=18 \\ x=(18)/(2) \\ x=9 \end{gathered}`

Hence, the solution is (9, -7).