Question

Find y' and y''. y = ln(sec(x) + tan(x))

Answer 1

\[y=\ln(\sec x+\tan x)\\
y'=\frac{\sec x\tan x+\sec^2x}{\sec x+\tan x}=\frac{\sec x(\tan x+\sec x)}{\sec x + \tan x}=\sec x\]
\(y''\) is easy to find from here.