Given the equations:
2x1 - 6x2 - x3 = - 38
- 3x1 - x2 + 7x3 = - 34
- 8x1 + x2 - 2x3 = - 20
(a) Solve by Gauss elimination with partial pivoting. Show all steps of the computation.
(b) Substitute your results into the original equations to check your answer.