## anonymous one year ago Where is the first derivative of y = 3xe−x equal to 0?

1. anonymous

okay so iv got the derivative (-3e^(-x))(x-1)

2. jim_thompson5910

So they gave you $\Large y = 3xe^{-x}$ right?

3. anonymous

yes

4. jim_thompson5910

I'm getting $\Large \frac{dy}{dx} = -3e^{-x}(x-1)$ as well

5. jim_thompson5910

now set dy/dx equal to 0 and solve for x

6. anonymous

yea well thats what i cant do

7. jim_thompson5910

$\Large \frac{dy}{dx} = -3e^{-x}(x-1)$ $\Large 0 = -3e^{-x}(x-1)$ $\Large -3e^{-x} = 0 \text{ or } x-1 = 0$

8. jim_thompson5910

I'm using the idea A*B = 0 means either A = 0 or B = 0

9. geerky42

Does that make sense? @Jdosio

10. anonymous

okay sorry just fell asleep in my desk yes iv got it thank you verry much:D