Question

b(a + b) - a(a - b)

Answer 1

Is there a question? o_O

Answer 2

(b-a)(a-b)^2

Answer 3

\[b(a+b)-a(a-b)\implies \color{blue}{ab+b^2-a^2+ab}\implies \color{red}{b^2-a^2+2ab.}\]