Answer:
(x - y)(x + y)(x² + y²)
Step-by-step explanation:
[tex]x^{4}[/tex] - [tex]y^{4}[/tex] ← is a difference of squares and factors in general as
a² - b² = (a - b)(a + b), thus
[tex]x^{4}[/tex] - [tex]y^{4}[/tex]
= (x²)² - (y²)²
= (x² - y²)(x² + y²) ← x² - y² is also a difference of squares, then
= (x - y)(x + y)(x² + y²)
