Question

Solve the system by substitution.
{x+y+2z=-7
-5x=25
3x-3y-6z=3

Answer 1

-5x = 25, so x = -5.
Substitute -5 for x in the first equation:
-5+y+2z = -7,
y+2z = -2
y = -2z-2

Substitute -5 for x in the third equation:
3(-5)-3y-6z = 3
-3y-6z = 18

Substitute -2z-2 for y
-3(-2z-2) -6z = 18
6 = 18, a contradiction
No solution