Answer:(a² - 4b² - 9)(a² - 4b² + 9)
(a^4 - 8a²b² + 16b^4) - 81
= [(a²)² - 2.4a²b² + (4b²)²] - 9²
= (a² - 4b²)² - 9²
= (a² - 4b² - 9)(a² - 4b² + 9)
Step-by-step explanation:
Answer:
[(a - 2b)(a + 2b) + 9)][(a - 2b)(a + 2b) - 9]
This can be written as the difference of 2 squares:
(a^4 - 8a^2b^2 + 16b^4) -81
= (a^2 - 4b^2)^2 - 81
=[(a^2 - 4b^2) + 9] [(a^2 - 4b^2) - 9]
= [(a - 2b)(a + 2b) + 9)][(a - 2b)(a + 2b) - 9]
