x + y + z = -1
2x - y + 2z = -5
-x + 2y - z = 4
There are a number of ways to solve this.
1. Straight elimination
2. Cramer's rule
3. Triangular method using equations
4. Triangular method using augmented method
5. Complete row reduced echelon form using metrices.
6. Inverse matrix method.
The answer is (x, y, z) = (-2-a, 1, a) where a is arbitrary.
Repost giving the method you are to use and we'll help you
go through the steps to get that answer by that method.
Edwin
