Suppose an n×n matrix a has determinant equal to 1. which of the following statements is true? check the correct answer(s) below. a. the system ax=b has a unique solution for all b in rn b. the matrix a is invertible c. the reduced row echelon form of the matrix a is the identity matrix d. the matrix a is singular. e. the homogeneous system ax=0 has infinitely many solutions f. none of the above