Can someone explain to me how we get the last line from the chain rule please? Thank you Sent from my SM-N910F using Tapatalk
Follow Math Help Forum on Facebook and Google+
You have: $\dfrac{dz}{d\tau} = \dfrac{dz}{d(1-\tau)}\dfrac{d(1-\tau)}{d\tau}$ The derivative of $1-\tau$ with respect to $\tau$ is -1, so the second term is -1.
Originally Posted by SlipEternal You have: $\dfrac{dz}{d\tau} = \dfrac{dz}{d(1-\tau)}\dfrac{d(1-\tau)}{d\tau}$ The derivative of $1-\tau$ with respect to $\tau$ is -1, so the second term is -1. Thanks! How come the first term doesn't change at all though? I thought with chain rule you have to take derivative of both functions? Sent from my SM-N910F using Tapatalk
You are "taking the derivative of both functions". $\frac{dz}{d(1- \tau)}$ is the first derivative and $\frac{d(1- \tau)}{d\tau}= -1$ is the second derivative.