Question

linear algebra: basis for nullspace of A? Suuppose A is a 4x5 matrix with rank 2 for which x1 = [1; 2; 3; 2; 1], x2=[1; -1; 0; 1; 2], x3 = [2; 1; 4; 4; 4] all satisfy Ax=0. Is the set S={x1, x2, x3} a basis for the nullspace of A? Justify your answer.