Question

resolva os sistemas

A)x+y=3

x-y=9

B)2m+3n=4
m+n=2


C)2x+3y=57
2y-x=38

D)x+y=7
x+2y=11

Answer 1

Boa dia

A)

x + y = 3
x - y = 9

2x = 12
x = 6
6 + y = 3
y = -3

B)

2m + 3n = 4
m + n = 2

2m + 2n = 4
3n - 2n = 0
n = 0

2m = 4
m = 2


C)

2x + 3y = 57
2y - x = 38

2x + 3y = 57
4y - 2x = 76

7y = 133
y = 133/7 = 19
2x + 3*19 = 57
2x + 57 = 57
x = 0

D)

x + y = 7
x + 2y =11

2y - y = 11 - 7
y = 4

x + 4 = 7
x = 3