a. Check all of the statements below that must be true if A is an m X n matrix with n pivot columns:
A. There exists an n X m matrix Y such that YA = I, where I denotes the n X n identity matrix.
B. The transformation xAx is injective (one-to-one).
C. The columns of A are linearly independent.
D. The transformation xAx is surjective (onto).
E. For any positive integer p and any p X m matrices X and Y, if XA = YA then X = Y.
b. Check all of the statements below that must be true if A is an m X n matrix with m pivot columns:
A. AA is invertible.
B. For any b ∈ R^m, the equation Ax = b has at least one solution.
C. For any b ∈ R^m, the equation Ax = b has at most one solution.
D. For any positive integer p and any p X m matrices X and Y, if XA = YA then X = Y.
E. AA is invertible.