e) a^2b^4 – 81a^2
e) a2b4 – 81a2
e) a2b4 – 81a2
= a2(b4 ‒ 81)
= a2[(b2)2 ‒ 92]
= a2(b2 + 9)(b2 ‒ 9)
= a2(b2 + 9)(b2 ‒32)
= a2(b2 + 9)(b ‒ 3)(b + 3).