Question

prove that (a+B) ^=a^+b^+2ab

Answer 1

You mean square.
Now
${(a + b)}^{2} = (a + b)(a + b) \\ = > a(a + b) + b(a + b) \\ = > {a}^{2} + ab + ba + {b}^{2} \\ = > {a}^{2} + {b}^{2} + 2ab$
hence proved.
Hope it help.