Functions Question 425

Question: The domain of the function $ f(x)=lo{g_{3+x}}(x^{2}-1) $ is

Options:

A) $ (-3,-1)\cup (1,\infty ) $

B) $ [-3,-1)\cup [1,\infty ) $

C) $ (-3,-2)\cup (-2,-1)\cup (1,\infty ) $

D) $ [-3,-2)\cup (-2,-1)\cup [1,\infty ) $

Show Answer

Answer:

Correct Answer: C

Solution:

[c] f(x) is to be defined when $ x^{2}-1>0 $ and $ 3+x>0 $ and $ 3+x\ne 1. $ i.e., $ x^{2}>1 $ and $ x>-3 $ and $ x\ne -2 $ , i.e., $ x<-1orx>1 $ and $ x>-3andx\ne -2 $
$ \therefore D_{f}=(-3,-2)\cup (-2,-1)\cup (1,\infty ) $