Question

resolva o sistema : 2x+y=13
x+y=8

Answer 1

2x+y=13
x+y=8 (-1)

2x+y=13
-x-y=-8

x=5

2x+y=13
2x5+y=13
10+y=13
y=13-10
y=3

S (5,3)

Answer 2

y=13-2x

x+13-2x=8
-x+13=8
-x=8-13
-x= -5 .(-1)
x=5

y=13- (2.5)
y=13-10
y= 3

(obs.: os pontos(.) representam o sinal de vezes)