The formula is a^2 - b^2 I got the answer for the b^2 but not a^2 I am getting 81x^4, where did I go wrong

Answer:
the answer is b^2 i don't know the answer either
Step-by-step explanation:
Answer:
9x^4 - 25/9x^6.
Step-by-step explanation:
3x^2 * 3x^2 = 9x^4 and
5/3x^3 * 5/3x^3 = 25/9x^6
The answer is 9x^4 - 25/9x^6.