Question

[7x - 3y = 6 | 2x - y = 3 resolva por substutuição

Answer 1

Resposta:

$2x-y=3\\2x=3+y\\x=\frac{3+y}{2}$

$7.(\frac{3+y}{2})-3y=6\\\frac{21+7y}{2}-3y=6 \\10,5+\frac{7y}2}-3y=6\\ \frac{7y}2}-3y=6 -10,5\\ \frac{7y}2}-3y=-4,5\\ \frac{6y-7y}{2}=-4,5\\ \frac{y}{2}=-4,5\\y=-4,5.2\\y=-9$