# Math Help - logarithmic differentiation

1. ## logarithmic differentiation

y= (sec x)^(x^4)

i did

ln y = x^4 (ln sec x)

and then what do i have to do?

2. Originally Posted by haebinpark
y= (sec x)^(x^4)

i did

ln y = x^4 (ln sec x)

and then what do i have to do?
take the derivative ...

$\frac{y'}{y} = x^4 \cdot \tan{x} + 4x^3 \ln(\sec{x})$

finish by multiplying both sides by $y$