Factor z2 - 3z - 18.

A. (z + 2) (z - 9)

B. (z + 3) (z - 6)

C. (z - 3) (z - 6)

D. (z + 8) (z - 10)

Your answer for this will be B (z+3) (z-6). Since the original equation has two negatives, the answer has to have one positive and one negative so the negatives don't cancel each other out and create a positive. To find the numbers in the parenthesis, you need to find something that multiplies to - 18 and also adds to - 3 at the same time. Choice B is correct because - 6x3=-18 and - 6+3=-3.

Answer is b!