If `A` and `B` are square matrices of the same order such that `A B=B A` , then show that `(A+B)^2=A^2+2A B+B^2` .

Explanation

`(A+B)^2=(A+B)(A+B)`

`=A^2+AB+BA+B^2`

`=A^2+AB+AB+B^2`

`=A^2+2AB+B^2`