Answer:
x^3 + 9x^3 -6x -54
Explanation:
first step is you're going to simplify the problem.
using the (a-b)(a+b)=a^2-b^2 formula combine the last two grouped numbers to equal (x+9)(x^2-6)
multiply the parenthesis to get x^3 - 6x + 9x^2 -54
reorder the terms and then you get your answer! x^3 + 9x^3 -6x -54
does this make sense? :)