Calculus (3rd Edition)

$$r=\frac{-12}{5+6 \cos \theta}.$$
Since $e=1.2$ and $d=-2$, then the polar equation in the standard form is $$r=\frac{e d}{1+e \cos \theta}=\frac{-2.4}{1+1.2 \cos \theta}=-\frac{24}{10+12 \cos \theta}.$$ Which simplifies to $$r=\frac{-12}{5+6 \cos \theta}.$$