Question

Resolva mentalmente os sistemas de equações abaixo A) x+y =10 x-y= 2 b)x+y=30x-y=10

Answer 1

A) x+y=10 e x-y=2

x=10-y

10-y-y=2 => -2y=-8 => y=4

x=10-y => x=10-4 => x=6

B) x+y=30 e x-y=10

x=30-y

30-y-y=10 => -2y=-20 => y=10

x=30-y => x=30-10 => x=20