First you have to reduce your matrix to row echelon form. The nonzero rows of this reduced matrix form a basis for . What are they?

Now the columns of this reduced matrix wih leading 1's identify the pivot columns of your original matrix. And these form a basis for . What are they?

Then the canonical solutions of Ax=0 form a basis for . These are readily obtained from the system Rx=0, where R is the reduced matrix of A).