Question

-11x-y+3z=-21
(5x-y-5z=-5)
(3x+y+z=13)

Answer 1

Answer:
`y=15-5x, z=2x-2`

Explanation:

Subtracting the first equation from the second equation yields
`16x-8z=16 \implies 2x-z=2 \implies z=2x-2`.

Substituting this into the first equation,

`-11x-y+3(2x-2)=-21\\\\-11x-y+6x-6=-21\\\\-5x-y-6=-21\\\\-5x-y=-15\\\\5x+y=15\\ \\ y=15-5x`