S.O.S. Mathematics CyberBoard

ive been trying this for a few hours but i dont think i grasp the concept of the basis...

1. Suppose that

A = [-8 0 -24 -8 -9
2 1 8 4 1
1 0 3 1 1
-1 1 -1 1 0]



a) Find a basis for ColA.
b) Find a basis for NulA.
c) Determine dim(ColA) and dim(NulA).

...now do i have to perform row operations to make this into row reduced echelon form? and then the pivot columns would be the Nul?

i think i know that the the dim for NulA would be the colums that are pivot colums after row reduced echelon form-am i right?

okay so i started doing row operations and am now at the following...

[1 -1 1 -1 -17/8
0 1 2 2 1/3
0 1 2 2 1
-1 1 -1 1 0]

if i add the last row to the first rwo, the last row will become 0 0 0 0 -17/8 and thus inconsistent..is that okay? or is that operation incorrect?