# Homework Help: Differentiation homework

1. Jul 20, 2010

### b521

1. The problem statement, all variables and given/known data

If y = x³ + 2x
and
dx/dt = 5,
find
dy/dt when x = 2.

3. The attempt at a solution

I'm not really sure how to solve this problem at all. It's the first I've seen like this so I don't know what approach I should take.

2. Jul 20, 2010

### hunt_mat

Re: Differentiation

Use the chain rule in the form:
$$\frac{dy}{dt}=\frac{dy}{dx}\frac{dx}{dt}$$

3. Jul 20, 2010

### b521

Re: Differentiation

Thank you so much!