Answer:
(4x^2 +9) (4x^2 -9) =0
Step-by-step explanation:
16x^4 - 81 =0
Rewriting
(4x^2) ^2 - 9^2 =0
This is the difference of squares a^2 -b^2 = (a+b)(a-b)
(4x^2 +9) (4x^2 -9)=0
