The resulting matrix for multiplying A and B has the same number of rows as A and the same number of columns as B

With matrices, multiplication is not commutative

Zero matrix can't come in all different shapes and sizes

Identity matrix can come in all different shapes and sizes

If AX = I (identity matrix), then A is called invertible

If AX = I (identity matrix), We can get the value of X if we do this operation (1/A)

which sentence is true

if A is a n x n matrix, then the reduced row echelon form of A is I (identity matrix)

if A is a n x n matrix, then the equation AX = b has exactly one solution for every n x 1 vector b

if A is a n x n matrix, then the equation AX = 0 has exactly one solution.

If A is invertible, then AX = b has exactly one solution, namely A^-1 b

If A is not invertible, then AX = b has no solution

If A is n x n invertible matrix, then KA is invertible for any nonzero scalar n; (KA)^-1 = (1/k)A^-1

if a product AB is not invertible, then A or B is not invertible.

if A or B are invertible, then AB can be invertible in one case

det(A) = …. A is a 2x2 matrix

A^-1 = 1/det(A) [d -b -c a]

det(A) =

det(A), A is a