Which of the following expressions is equivalent to $-4x^3-12x^3+9x^2$ ?

$x^8$

$-7x^8$

$-8x^3+9x^2$

$-16x^3+9x^2$

$-16x^6+9x^2$

Approach

$$ -4x^3-12x^3+9x^2 $$

We can only combine the cubic term here:

$$ (-4-12)x^3+9x^2 $$ $$ = \boxed{-16x^3+9x^2} $$