Answer
$\dfrac{x^{3}-4x}{x^{2}+3x+2}=\dfrac{x(x-2)}{x+1}$
Work Step by Step
$\dfrac{x^{3}-4x}{x^{2}+3x+2}$
Take out common factor $x$ from the numerator and factor the denominator:
$\dfrac{x^{3}-4x}{x^{2}+3x+2}=\dfrac{x(x^{2}-4)}{(x+2)(x+1)}=...$
Factor $x^{2}-4$ in the numerator and simplify:
$...=\dfrac{x(x-2)(x+2)}{(x+2)(x+1)}=\dfrac{x(x-2)}{x+1}$
