Question

Solve 1. D
Fast pls fast

Answer 1

$\mathbf{{({m}^2-{n}^2)}^2}$
$\mathbf{Identity of {(a-b)}^2={a}^2+{b}^2-2ab}$
$\mathbf{And\: if ({a}^2-{b}^2)={({a}^2)}^2+{(b^2)}^2-2{a}^2{b}^2}$
And if
(m²-n²)²
=(m²)²+(n²)²-2m²n²
=m⁴+n⁴-2m²n²

$\boxed{\mathbf{{m^4}+{n^4}-2{m}^2{n}^2}}$