Answer:
C. (x - 9)(x^2 + 9x + 81).
Step-by-step explanation:
The cube identities are
a^3 - b^3 = (a - b)(a^2 + ab + b^2)
a^3 + b^3 = (a + b)(a^2 - ab + b^2)
Checking against the list the one that fits is the difference formula:
x^2 - 9^2 = (x - 9)(x^2 + 9x + 81).
a=1, b = 9, ab = 1 *9 = 9.
