Functions Question 435

Question: The function $ f(x)=log( x+\sqrt{x^{2}+1} ) $ , is

Options:

A) neither an even nor an odd function

B) an even function

C) an odd function

D) a periodic function

Show Answer

Answer:

Correct Answer: C

Solution:

[c] $ f(x)=log(x+\sqrt{x^{2}+1}) $ $ f(-x)=log{ -x+\sqrt{x^{2}+1} }=\log { \frac{-x^{2}+x^{2}+1}{x+\sqrt{x^{2}+1}} } $ $ =-\log (x+\sqrt{x^{2}+1})=-f(x)\Rightarrow f(x) $ is an odd function.