Question

determine a solução de cada sistema a) {2x-y=9 x-y=5} b) { x-x+y=-2 2x-3y=1} c) {2x-y=9 x-y=5}

Answer 1

a)
2x-y=9 (.-1)
x-y=5 (.2)

-2x+y=-9
2x-y=10
sistema impossível!

b)
-x+y=-2 (.2)
2x-3y=1 (.1)

-2x+2y=-4
2x-3y=1

-y=-3 (.-1)
y=3

-x+3=-2
-x=-2-3
-x=-5 (.-1)
x=5

S=(5, 3)


c)
2x-y=9 (.-1)
x-y=5 (.2)

-2x+y=-9
2x-2y=10

-y=1 (.-1)
y=-1

2x-(-1)=9
2x=9-1
2x=8
x=8/2
x=4

S=(4, -1)