Answer:
Both C and D are factors of the binomial above.
Step-by-step explanation:
In order to find this, note that the original is difference of two squares. In order to find the binomials that come from this, you simply need to take the square root of the first and the second term.
√81x^2 = 9x
√36 = 6
Now that we have this, we can stick them in parenthesis together with alternating signs.
(9x - 6)(9x + 6)
