Question

For 2X2 matrices A, B, and C, and scalars k and x, which of the following statements is not true?
(a+b)(a-b)=A^2-B^2
k(A+B)=kA+kB
a(BC)=(AB)C
A(B+C)=AB+AC
(k+l)A=kA+lA

Answer 1

I assume a and b are really A and B?
To answer this, you must know that (in general) AB ≠ BA