Are the following statements true or false? Justify your answer. (a) A is a m x n matrix. If P is the projection matrix onto N(A), then for any vector r R", we have Pa -ax lives in C(AT) (b) If Ax = b has a solution x, then the closest vector in N(AT) to b is 0. (c) If matrix U has orthonormal rows, then UUT-I. x lives in C(A)