Question

Resolver os sistemas :

a- x-y=3
2x+y=9

B- x+y=10
2x-y=8

C- 4x+y=7
2x-5y=9

E- x-3y=9
2x+3y=6

Answer 1

a) {x-y=3
{2x+y=9
x-y=3.(-2)
{-2x+2y=-6
{2x+y=9
3y=3
y=3/3
y=1
x-y=3
x-1=3
x=3+1
x=4
S={(4, 1)}
b) {x+y=10
{2x-y=8
3x=18
x=18/3
x=6
x+y=10
6+y=10
y=10-6
y=4
S={(6, 4)}
c) {4x+y=7
{2x-5y=9
4x+y=7.(5)
{20x+5y=35
{2x-5y=9
22x=44
x=44/22
x=2
4x+y=7
4.2+y=7
8+y=7
y=7-8
y=-1
S={(2, -1)}
e) {x-3y=9
{2x+3y=6
3x=15
x=15/3
x=5
x-3y=9
5-3y=9
-3y=9-5
-3y=4.(-1)
3y=-4
y=-4/3
S={(5, -4/3)}