Thanks to all of you who support me on Patreon. You da real mvps! $1 per month helps!! 🙂 https://www.patreon.com/patrickjmt !! Curve Sketching Using Calculus: f(x) = x / (x + 4). In this video, I show how to use a bit of algebra and calculus to sketch a rational function. We look at x,y intercepts, horizontal/vertical asymptotes, domain, regions of increase/decrease and concavity.