Exercício 1. Resolva os seguintes sistemas lineares, efetuan...

Exercício 1. Resolva os seguintes sistemas lineares, efetuando a prova real ao final: (a) $\left\{\begin{array}{l}x+2 y=8 \\ 2 x+y=7\end{array}\right.$ (b) $\left\{\begin{array}{l}3 x+5 y=7 \\ x-y=5\end{array}\right.$ (c) $\left\{\begin{array}{l}2 x-y=13 \\ x+y=17\end{array}\right.$ (d) $\left\{\begin{array}{l}x-y=5 \\ 3 x-4 y=12\end{array}\right.$ (e) $\left\{\begin{array}{l}3 x-4 y=-17 \\ -2 x+y=3\end{array}\right.$ (f) $\left\{\begin{aligned} 4 x-6 y & =0 \\ 3 x-5 y & =-1\end{aligned}\right.$ (g) $\left\{\begin{array}{l}2 x+3 y=-5 \\ x+2 y=-2\end{array}\right.$ (h) $\left\{\begin{aligned} 4 x+12 y & =5 \\ 4 x-12 y & =-3\end{aligned}\right.$