Finding Derivative, but wrong sign

[gr3g1]

Ok, I am 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 don't get it

 

[quantumdude]

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.

 

[gr3g1]

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