[SOLVED] Solving if a matrix is infinite

x + y + z = 4

2x + 3y + z = 8

3x + (3-p)y + 2z = 13-(p^2)

I've reduced the system of equations to:

x + y + z = 4

y - z = 0

(p+1)y = (p^2) - 1

It then says:

"For each of p = 1 and p = -1 indicate how many solutions there are to the system of equations. I there is a unique solution, give that solution. If there are infinitely many solutions give the resulting unique solution when

(i) z = 1

(ii) z = -1

I've found that p=1 give unique and p = -1 give infinite.

PS. My elimination is fine I have the answers.

(i) z = 1, y = 1, x = 6

(ii) z = -1, y = -1, x = 6

I just don't know how to solve if it is infinite.