Question

Factorise.
$a^4-2a^2{b}^2+b^4$

Answer 1

$a^4-2a^2{b}^2+b^4$

$=(a^2{)}^2-2a^2{b}^2+(b^2{)}^2$

$=(a^2-b^2{)}^2$

$=\left[\right(a-b\left)\right(a+b){]}^2$

$=(a-b{)}^2(a+b{)}^2$

$=(a-b)(a-b)(a+b)(a+b)$