Answer:
The answer is A
Step-by-step explanation:
The next term is double the previous term, so that the
-th term is given recursively by

This rule tells us that



and so on, with the explicit rule

for
.
If 512 is the
-th term in the sequence, then

We notice a factor of 2x in both
2x(5x^2+4x-3)
trial and error
(5x-3)(x+1) yeilds 5x^2+2x-3, nope
(5x+3)(x-1) yeilds 5x^2-2x-3, nope
(5x-1)(x+3) yeilds 5x^2+14x-3, nope
(5x+1)(x-3) yeilds 5x^2-14x-3, nope
simplest form is
2x(5x^2+4x-3)