Question

Solve the following system of equations for all three variables.

5x−2y+z = 8
−9x+2y+2z = 5
−9x−2y−5z = 4

Answer 1

5x - 2y + 1z = 8 ⇒ 5x - 2y + 1z = 8
-9x + 2y + 2z = 5 ⇒ -9x + 2y + 2z = 5
-9x - 2y - 5z = 4 -4x + 3z = 13

5x - 2y + 1z = 8
-9x + 2y + 2z = 5 ⇒ -9x + 2y + 2z = 5
-9z - 2y - 5z = 4 ⇒ -9x - 2y - 5z = 4
-18x - 3z = 9

-4x + 3z = 13
-18x - 3z = 9
-22x = 22
-22 -22
x = -1
-18x - 3z = 9
-18(-1) - 3z = 9
18 - 3z = 9
- 18 - 18
-3z = -9
-3 -3
z = 3

5x - 2y + z = 8
5(-1) - 2y + 3 = 8
-5 - 2y + 3 = 8
-2y - 5 + 3 = 8
-2y - 2 = 8
+ 2 + 2
-2y = 10
-2 -2
y = -5
(x, y, z) = (-1, -5, 3)