A.0 =

A.I =

I.A =

I^2 =

In general A.B = B.A

In matrices Multiplication is commutative

A.I = I.A = A

I is called

In general, just because AX = BX, we cannot conclude that A = B

The nxn matrix with 1’s on the diagonal and zeros elsewhere is the nxn ….

the identity matrix can be either a square matrix or not a square matrix

A(BC) = (AB)C

A(B+C) = AB + AC

A^3 = A.A.A

A^0 =

AX = I, so A is invertible

AX = I, so X is the inverse of A

AX = I, so A and X have the same size

if AX = I, then XA = I

AX = I, then A and X are squared matrices

in 2x2 matrix if ad-bc = 0 The matrix can has an inverse