How does the chain rule apply to logarithmic differentiation?

[Owen-]

Hi everyone - I'm in my first year at uni, and I was given a derivative that i don't quite get:

y(x) is a function of x then
y` = (dy/dx)

d/dx (ln y(x))=1/y(x)*(dy/dx) =(y`/y)


This is given by the chain rule. I don't understand this step...

Any help?

Thanks in advance,
Owen.

 

[VanOosten]

chain rule says deriver the outside function first (the ln y part)
then do the derivative of the inside function (the y(x))
d/dx(ln y(x))
= d/dx(ln y)*d/dx (y(x))
=1/y *y'(x)

 

[Owen-]

Thanks, just needed to have that put another way - makes perfect sense - thanks again