Question

resolva os sistemas

C)x+y=7
2x-y=5

D)x+y=9
x-y=3

E)x-3y=6
2x+y=5
POR FAVOR URGENTE

Answer 1

c) {x+y=7
{2x-y=5
3x=12
x=12/3
x=4
x+y=7
4+y=7
y=7-4
y=3
S={(4, 3)}
d) {x+y=9
{x-y=3
2x=12
x=12/2
x=6
x-y=3
6-y=3
-y=3-6
-y=-3.(-1)
y=3
S={(6, 3)}
e) {x-3y=6
{2x+y=5
x=6+3y
2(6+3y)+y=5
12+6y+y=5
6y+y=5-12
7y=-7
y=-7/7
y=-1
x=6+3y
x=6+3.(-1)
x=6-3
x=3
S={(3, -1)}