Question

How to Factorise these?? (with clear process)

Answer 1

Here is your answer,

X^4+y^4-27x^2y^2

=X^4-2x^2y^2+y^4-25x^2y^2

=(X^2+y^2)^2-(5xy)^2

=(X^2+y^2+5xy)(x^2+y^2-5xy)

Answer 2

x^4+y^4-27x^2y^2
=x^4-2x^2+y^4-25x^2y^2
=(x^2+y^2)^2-(5xy)^2
=(x^2+y^2+5xy)(x^2+y^2-5xy)