Question

We want to find the zeros of this polynomial:
p(x)= 3x^3 – 3x^2– 18x

Answer 1

x = -2, 0, 3.

Explanation:

3x^3 – 3x^2– 18x = 0

First take out the GCF which is 3x:

3x(x^2 - x - 6) = 0

So one zero is 0 ( because 3x = 0).

x^2 - x - 6 = 0

(x - 3)(x + 2) = 0

x = -2, 3.

Answer 2

x=0 x=3 x=-2

Explanation:

p(x)= 3x^3 – 3x^2– 18x

Factor out the greatest common factor, 3x

p(x)= 3x (x^2 – x– 6)

Factor inside the parentheses

What 2 numbers multiplies to -6 and adds to -1

-3*2 = -6

-3+2 = -1

p(x)= 3x (x-3)(x+2)

Setting the function equal to zero to find the zeros

0 = 3x (x-3)(x+2)

Using the zero product property

3x = 0 x-3 =0 x+2 =0

x=0 x=3 x=-2