Applications Of Derivatives Question 213

Question: If $ I_{n}=\frac{d^{n}}{dx^{n}}(x^{n}\log x), $ then $ I_{n}-n{I_{n-1}}= $

[EAMCET 2003]

Options:

A) $ n $

B) $ n-1 $

C) $ n! $

D) $ (n-1)! $

Show Answer

Answer:

Correct Answer: D

Solution:

$ I_{n}=\frac{{d^{n-1}}}{d{x^{n-1}}}[{x^{n-1}}+n{x^{n-1}}\log x] $

$ I_{n}=(n-1)!+n{I_{n-1}} $

therefore $ I_{n}-n{I_{n-1}}=(n-1)! $ .