1. ## chain rule derivatives...

y() = e sin(8)

for this one i got 8e^(theta)*cos(8theta)...

but it was wrong, what did i do wrong??

2. You have neglected the fact that there is a product of functions.

If f(x) = g(x)*h(x), then f'(x) = g(x)*h'(x) + g'(x)*h(x).

Ringing any bells?

3. Originally Posted by TKHunny
You have neglected the fact that there is a product of functions.

If f(x) = g(x)*h(x), then f'(x) = g(x)*h'(x) + g'(x)*h(x).

Ringing any bells?
can you do it for me so i can see...

4. Hello, mathaction!

Have you forgotten the Product Rule?

$\displaystyle y \:=\:e^{\theta}\!\cdot\!\sin(8\theta)$

We have: .$\displaystyle \frac{dy}{d\theta} \;=\;e^{\theta}\cdot\cos(8\theta)\cdot8 + e^{\theta}\cdot\sin(\theta) \;=\;e^{\theta}\left[8\cos(8\theta) + \sin(\theta)\right]$