# How do you use the formula (ln f(x))'= f'(x) / f(x) to show that lnx and ln(2x) have the same derivative?

##### 1 Answer

Jun 9, 2016

We know that:

#(lnf(x))'=(f'(x))/f(x)#

So, for

Thus:

#(lnx)'=1/x#

For

Thus:

#(ln(2x))'=2/(2x)=1/x#