Don't know the steps in finding this derivative.
But the derivative is
The answer is:
n
/ 1\ / 1 / 1\\
|1 + -| *|- --------- + log|1 + -||
\ n/ | / 1\ \ n/|
| n*|1 + -| |
\ \ n/ /
n / 2 \
/ 1\ |/ 1 / 1\\ 1 |
|1 + -| *||- --------- + log|1 + -|| - -----------|
\ n/ || / 1\ \ n/| 2|
|| n*|1 + -| | 3 / 1\ |
|\ \ n/ / n *|1 + -| |
\ \ n/ /
/ / 1 / 1\\\
| 3*|- --------- + log|1 + -|||
| | / 1\ \ n/||
n | 3 | n*|1 + -| ||
/ 1\ |/ 1 / 1\\ 2 3 \ \ n/ /|
|1 + -| *||- --------- + log|1 + -|| - ----------- + ----------- - ----------------------------|
\ n/ || / 1\ \ n/| 3 2 2 |
|| n*|1 + -| | 5 / 1\ 4 / 1\ 3 / 1\ |
|\ \ n/ / n *|1 + -| n *|1 + -| n *|1 + -| |
\ \ n/ \ n/ \ n/ /