Question

Resolva os seguintes sistemas:
4x-y=8
x+y=7

Answer 1

-y=8-4x
+y=-8+4x

x+(-8)+4x=7
x+4x=7+8
5x=15
x=$\frac{15}{5}$
x=5

y=-8+4×5
y=-8+20
y=12

$x = 5 \\ y = 12$