Question

Resolva o sistema de equações do 1º grau abaixo e calcule x (x + 2y = 1287 (2x - y = 1859​

Answer 1

$\large\boxed{\begin{array}{l}\begin{cases}\sf x+2y=1287\\\sf 2x-y=1859\end{cases}\\\\+\underline{\begin{cases}\sf x+\diagdown\!\!\!\!\!2y=1287\\\sf 4x-\diagdown\!\!\!\!2y=3718\end{cases}}\\\sf 5x=5005\\\sf x=\dfrac{5005}{5}\\\\\sf x=1001\\\sf 2x-y=1859\\\sf y=2x-1859\\\sf y=2\cdot1001-1859\\\sf y=2002-1859\\\sf y=143\\\sf S=\{(1001,143)\}\end{array}}$