Question

resolva o sistema 2x+3y=4 x-4y=15

Answer 1

2 x + 3 y = 4
x - 4 y  = 15
x = 15 + 4 y 
substitui x
2 x + 3 y = 4
2 (15 + 4 y )  + 3 y = 4
30 + 8 y + 3 y = 4
30 + 11 y = 4
11 y = 4 - 30
11 y = -26
y = -26/11 
substitui y
x = 15 + 4 y 
x = 15 + 4 . (-26/11)
x = 15  - 104 / 11
m.m.c = 11
x = 165/11 - 104/11
x = 61/11