Answer:
see explanation
Step-by-step explanation:
Note that (x² + 5)(x² - 5) are the factors of a difference of squares
a² - b² = (a + b)(a - b)
with a = x² and b = 5, hence
(x² + 5)(x² - 5) = (x²)² - 5² = [tex]x^{4}[/tex] - 25, thus
3([tex]x^{4}[/tex] - 25) = 3[tex]x^{4}[/tex] - 75
