Question

Resolva o sistema x-y=84 x-3y=16

Answer 1

$\left \{ {{x\ -\ y\ =\ 84} \atop {x\ -\ 3y\ =\ 16\ (-1)}} \right.\\ \\ \downarrow \\ \\ \left \{ {{x\ -\ y\ =\ 84} \atop {-x\ +\ 3y\ =\ -16}} \right.\\ \line(180,0){70}\\ 2y\ =\ 68\\ y = \frac{68}{2} \\ y = 34\\ \\ x - y = 84\\ x - 34 = 84\\ x = 84 + 34\\ x = 118\\ \\ \boxed{Resposta: x = 118; y = 34}$