Answer:
(9p -5q)(9p +5q)
Explanation:
The difference of squares is a special form with the factoring ...
... a^2 -b^2 = (a -b)(a +b)
Here, you have ...
- a = 9p . . . . . . you recognize that 81p^2 = (9p)^2
- b = 5q
so the factoring is ...
... 81p^2 - 25q^2 = (9p -5q)(9p +5q)