Will give 50 i'm stuck with this question and i don't get

His answer was (x- +2) (x^2-9)

a) His mistake was he has x^2 in one of the parenthesis, to be fully factored you cannot have an exponent as part of the answer.

b) x^3 - 9x + 2x^2 -18

Reorder the terms:

x^3 +2x^2 -9x -18

Group the first two terms and the last two terms

(x^3 + 2x^2) -9x-18

Factor out the greatest common factor from each group:

x^2(x+2) - 9(x+2)

Factor the polynomial by factoring out the common factor once x+2:

(x+2) (x^2-9)

Rewrite 9 as 3^2:

(x+2) (x^2-3^2)

Factor one last time:

(x+2) (x+3) (x-3)

find out the value of b

step-by-step explanation:

the final function for the graph becomes x-2=-1. before graphing you solve the equation, where x=1. then graph accordingly.   ( on the x-axis, 1 on the line will possess a vertical line.)