Question

y=1/log(cos x)
dy/dx=?
answer in book is= tan x/[log(cos x)]^2
i took 1= ln e and then lnA/lnB=ln (A-B)
then chain rule i cant convert my anwer to the one given, am i right? or i made a mistake?

Answer 1

What's the base of your log 10?

Answer 2

nah.. e ie Euler's number

Answer 3

why don't you use the change of base formula?

Answer 4

it is log to base e every where.. even in question it is log to base e

Answer 5

That is fine but \[\log_a x= lnx/lna\]

Answer 6

SO that you have \[\ln(cosx)/lne\]
and \[lne\] is just 1

Answer 7

\[y= 1/\ln(cosx)\]