Solve by Substitution Method:
4x − 4y + 4z = −4 ------------ (1)
4x + y −2z = 5 ------------ (2)
−3x − 3y − 4z = −16 -------- (3)
Substituting for y = -4x + 2z + 5, from (2), into (1) and (3) gives us
9x – 10z = -1 --------- (4)
5x – z = 4 ------------ (5)
Substituting for z = 5x – 4, from (5), into (4) gives us
9x – 50x + 40 = -1
-41x = -41
x = 1
z = 5x – 4 = 5 – 4
z = 1
y = -4x + 2z + 5 = -4 + 2 + 5
y = 3
Solution is: x = 1, y = 3, z = 1