Question

resolva o sistema e assinale a alternativa correta:{5x+4Y=3x-2y=12

Answer 1

5 x + 4 y = 3
x - 2 y  = 12
x = 12 + 2 y

substituir  x
5 .(12 + 2 y ) + 4 y = 3
60 + 10 y + 4 y = 3
14 y = 3 - 60
14 y = -57
y = -57/14
x - 2 y = 12
x - 2 (-57/14) = 12
x  + 114/14 = 12
x = 12 - 114/14
x = 168/14 - 114/14
x = 54/14 =27/7