Question

What is y^4-36 in simplest factored form?

Answer 1

$y^4-36=(y^2)^2-6^2=(y^2-6)(y^2+6)=[y^2-(\sqrt6)^2](y^2+6)\\\\=(y-\sqrt6)(y+\sqrt6)(y^2+6)\\\\\\\\\\a^2-b^2=(a-b)(a+b)$