# Finding Derivative, but wrong sign

1. Nov 4, 2005

### gr3g1

Ok, Im doing my calculus homework, but sometimes I get a negative in the wrong place...
Here is an example:
The solution I got for the derivative attached is on the numerator:
5e^x(9e^x)-5e^x(4+9e^x)
In the solution, the negative sign is on the other side??
I dont get it

File size:
3.1 KB
Views:
51
2. Nov 4, 2005

### Tom Mattson

Staff Emeritus
You are probably misapplying the quotient rule, which is:

$$\frac{d}{dx}\left(\frac{f}{g}\right)=\frac{f'g-fg'}{g^2}$$

It does matter in which order you place the terms in the numerator.

3. Nov 4, 2005

### gr3g1

Damn!
I didnt know that! Thanks a lot man!