Hey mate. Try this answer. Let me know if it helps you.
64a^2-81^2
Rewrite 64a^2 as (8a)^2
(8a)^2-81b^2
Rewrite 81b^2 as (9b)^2
(8a)^2-(9b)^2
Since both terms are perfect squares, factor using the difference of squares formula, a^2-b^2=(a+b)(a-b)where a=8a and b=9b.
(8a+9b) (8a-(9b))
Multiply 9 by -1.
(8a+9b)•(8a-9b)
So your answer is a) 8a+9b.
Hope this helps.
