Question

Factorize.
(i) $a^4-b^4$

Answer 1

$a^4-b^4$

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

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

$=(a^2+b^2)(a-b)(a+b)$.