Question

2x-5=y-4 em baixo desse 7x-y=y+3

Answer 1

2 x - 5 = y - 4  →y - 4 = 2 x - 5   →y = 2 x - 5  + 4  →y = 2 x - 1
7 x - y = y + 3  →7 x - y  - y  = 3  → 7 x - 2 y = 3
7 x  - 2 y = 3
7 x - 2 ( 2 x - 1 ) = 3
7 x - 4 x + 2 = 3
3 x + 2  - 3 =0
3 x - 1 = 0
3 x = 1
x = 1/3
y = 2 x - 1
y = 2 .1/3 - 1 m.m.c =3
y = 2/3 - 3/3
y = -1/3
S={1/3,- 1/3}