Question

what is the factored form of this expression?
$-9x^3 - 12x^2 - 4x$

a. $x(3x - 2)^2$

b. $x(3x - 2)(3x + 2)$

c. $-x(3x + 2)^2$

d. $-x(3x - 2)(3x + 2)$

Explanation:

Step1: Factor out common term

$-9x^3 - 12x^2 - 4x = -x(9x^2 + 12x + 4)$

Step2: Factor quadratic trinomial

Notice $9x^2+12x+4=(3x)^2+2(3x)(2)+2^2=(3x+2)^2$

Answer:

C. $-x(3x + 2)^2$