HOW TO FACTOR GROUPING?

Question

x^2(x^4+3y^4)-y^2(y^4+3x^4)

Answer 1

x^2(x^4+3y^4)-y^2(y^4+3x^4)

x^6 + 3x^2 y^4 - y^6 - 2x^4y^2

x^6 - x^4y^2 + x^2y^4 - y^6 + 2x^2y^4 - 2x^4y^2

x^4(x^2 - y^2) + y^4(x^2 - y^2) + 2x^2y^2(y^2 - x^2)

(x^2 - y^2)(x^4 + y^4 - 2x^2y^2)

(x^2 - y^2)(x^2 - y^2)^2

(x^2 - y^2)^3

Answer: (x^2 - y^2)^3