how to make factor of this expression

Question

How do I factor $x^4 + x^2 y^2 + y^4$? And in how many ways can I make the factor?

Some methods I know are

1. Mid term Break
2. Substiturion Method
3. Quadratic Equation

Answer 1

Hint: $x^4 + x^2 y^2 + y^4 = (x^4 + 2 x^2 y^2 + y^4) - x^2 y^2$.

Answer 2

Hint: $x^4+x^2+1=\left( {x}^{2}+x+1 \right) \left( {x}^{2}-x+1 \right) $