# Parametric derivatives

Registered User regular
edited April 2012
I've asked a couple instructors at my school and they didn't really have a satisfactory answer for me. hoping someone here can clarify for me or point me in the right direction.

1st derivative of a parametric equation is dy/dx = (dy/dt)/(dx/dt) which I understand. The problem comes with the 2nd derivative.

d^2y/dx^2 = d/dx(dy/dx) = (d/dt(dy/dx))/(dx/dt)

I'm not following the path from the 2nd to the 3rd step. I can calculate the 2nd derivative, I just don't see how the formula is derived.

Carpy on

## Posts

• Building Planet Busters Tasting FruitRegistered User regular
Because you're taking a derivative of a quotient of functions: http://en.wikipedia.org/wiki/Quotient_rule

You're basically calculating the derivative of: dydx = y'(t) / x'(t)

• Registered User regular
Thanks for the tip, I spent a bit screwing around with the quotient rule and not seeing it, but I did meet with a different professor who was able to walk me through the derivation using the chain rule, renaming of some terms, and some calc 3 concepts. Haven't taken that class but she showed me enough to satisfy my curiosity. this could be locked now.