Math Help - Differentiate the function -

1. Differentiate the function -

y = ln(4x/5-3x)

What I have done is -

ln4x - ln(5-3x)

= dy/dx = 1/4x - 1/(5-3x)

= (5-3x-4x)/4x(5-3x)

I hope I have posted this in the right place, my apologies if not?

2. Re: Differentiate the function -

U have to use the chain rule, because you're dealing with composite functions:
You're first step is good. But then it went wrong, because you didn't use the chain rule:
If you want to calculate for example:
$D[\ln(5-3x)]$
Let $5-3x=u$
so you get:
$D[\ln(u)]=\frac{Du}{u}=\frac{D(5-3x)}{5-3x}= \frac{-3}{5-3x}$

Use also the chainrule to calculate $D[\ln(4x)]$ or notice that
$\ln(4x)=\ln(4)+\ln(x)$