Question

resolva:

A) 2×+7y=17
5×-y=-13

B) 2×-2y=4
4×-3y=3

C) ×+y=-3
3×+y=1

Answer 1

a) 2x + 7y = 17 .(5)
    5x - y = -13 .(-2)

10x + 35y = 85
-10x + 2y = 26

35y = 85
2y = 26
37y = 111
y = 111 : 37
y = 3

2x + 7. 3 = 17
2x + 21 = 17
2x = 17 - 21
2x = 4
x = 4 : 2
x = 2