Question

8) -7x-2y=-13 x-2x= 11 1

Answer 1

$\begin{cases}-7x-2y=-13 \\ x-2y=11\end{cases}\rightarrow\begin{cases}7x+2y=13 \\ x-2y=11\end{cases}\rightarrow8x=24\rightarrow x=\frac{24}{8}=3$

having that x=3 we get

$3-2y=11\rightarrow-2y=11-3=8\rightarrow y=-\frac{8}{2}=-4$

so the answer is x=3 and y=-4

$x-2y=11\rightarrow x=11+2y$

having that we can replace in the first equation

$\begin{gathered} -7\cdot(11+2y)-2y=-13\rightarrow-77-14y-2y=-13\rightarrow-16y=64 \\ y=-\frac{64}{16}=-4 \end{gathered}$

having that y=-4 we get

$x=11+2\cdot-4=11-8=3$