\(\dfrac{d}{dx}[\dfrac{a}{b}] = \dfrac{b\dfrac{da}{dx} - a\dfrac{db}{dx}}{b^{2}}\)
\(ex. a\)
\(\dfrac{d}{dx}[\dfrac{6x}{x + 3}] =\)
\(\dfrac{(x + 3)(6) - (6x)(1)}{(x + 3)^{2}}\)
\(\dfrac{6x + 18 - 6x}{(x + 3)(x + 3)}\)
\(\dfrac{18}{x^{2} + 6x + 9}\)
