Answer:
(3) (4x - 9)(4x + 9)
Step-by-step explanation:
4x times 4x will give you 16x^2, and 9 times 9 is 81, but you need to have one of the nines negative to give you the -81.
You needed the square root of 16 and the square root of x^2, then the square root of 81.
