The derivative of ln(u) is 1/u * the derivative of u.
[tex]y = ln(sec(x)+tan(x)) \\ \\
y' = \frac{1}{sec(x)+tan(x)} * [tan(x)sec(x) + sec^2(x)] \\ \\
y' = \frac{sec(x)(sec(x) + tan(x))}{sec(x)+tan(x)} \\ \\
y' = sec(x) + C[/tex]
I hope this helps! :)
