(a) Suppose that the augmented matrix for a system of equations reduces to

row1 1 0 0 0 -1

row2 0 1 0 0 2

row3 0 0 1 0 0

row4 0 0 0 1 -4

:

Write the solution if the variables are x; y; z and w, respectively.

(b)What is the solution to the system in (a) if the second row is replaced by

0 0 0 0 1 ?

(c) What is the solution to the system in (a) if the second row is replaced by

0 0 0 0 0 ?