12. Consider the matrix A3 4 4 7 whose reduced row echelon form is rref (A)- You do NOT 4 5 5 9 have to verify this. Answer the following (a) Find a basis for the null space of A (b) Find a basis for the column space of A (c) What is the dimension of the l space of A? (d) What is the dimension of the column space of A? (e) Is the matrix A invertible? Explairn (f) Compute the determinant of A