Question

Factorise the following trinomials:
$49x^4-168x^2{y}^2+144y^4$

Answer 1

$49x^4-168x^2{y}^2+144y^4$

$={\left(7x^2\right)}^2-2\times 7x^2\times 12y^2+{\left(12y^2\right)}^2$

$={(7x^2-12y^2)}^2$