# Thread: Help with a differentiating question.

1. ## Help with a differentiating question.

Find dy/dx if
(attachment)

Many thanks!

2. ## Differentiating

Hi-

Just differentiate $2y^3t+t^3y=1$ with respect to $x$, using the product rule to get:

$2y^3\frac{dt}{dx}+3y^2\frac{dy}{dx}t +t^3\frac{dy}{dx}+3t^2\frac{dt}{dx}y=0$

Now collect together the terms in $\frac{dt}{dx}$ and $\frac{dy}{dx}$, substitute $\frac{dt}{dx}=\frac{1}{\cos t}$ and the job's done.