I'm having trouble with this question

5. Consider the matrices 3 6 1 1 1 2 0 1 0 A: 1 2 2 3 1 and B: D 0 1 2 D . 2 4 5 8 4 0 0 0 0 1 You may take it for granted that B is the reduced-row echelon form of A. (a) (4 marks) Write down bases for Col(A) and Null(A) (show your working). (b) (3 marks) Suppose A = MCB(L) where L : 134(1R) ) R3 is a linear map, 3 is a basis for 'P4 (IR), and C is a basis for R3. Prove that im(L) = R3. (c) (2 marks) Null(A) is isomorphic to EAR) for some n. Write down the value of n and write down an isomorphism L : Null(A) ) PAR) (you do not need to justify your answer here)