10x-y+2z=11
x+2y-z=11
2x+2y-3z=19
last problem of my homework please help.
2x + 2y - 3z = 19
x + 2y - z = 11
==> x - 2z = 8
20x - 2y + 4z = 22
==> 21x + 3z = 33
x - 2z = 8
21x + 3z = 33
==> 21 (8 + 2z) 3z = 33 ==> z = -3
x = 8 + 2z = 8 - 6 = 2
y = 10x + 2z - 11 = 20 - 6 - 11 = 3
Answer: x = 2, y = 3, z = -3
Comments
2x + 2y - 3z = 19
x + 2y - z = 11
==> x - 2z = 8
20x - 2y + 4z = 22
x + 2y - z = 11
==> 21x + 3z = 33
x - 2z = 8
21x + 3z = 33
==> 21 (8 + 2z) 3z = 33 ==> z = -3
x = 8 + 2z = 8 - 6 = 2
y = 10x + 2z - 11 = 20 - 6 - 11 = 3
Answer: x = 2, y = 3, z = -3