Answer:
(x² - 3)(x² + 3)([tex]x^{4}[/tex] + 9)
Step-by-step explanation:
[tex]x^{8}[/tex] - 81 ← is a difference of squares and factors in general as
a² - b² = (a - b)(a + b)
[tex]x^{8}[/tex] - 81
= ([tex]x^{4}[/tex] )² - 9²
= ([tex]x^{4}[/tex] - 9)([tex]x^{4}[/tex] + 9) ← [tex]x^{4}[/tex] - 9 is also a difference of squares
= (x² - 3)(x² + 3)([tex]x^{4}[/tex] + 9)