Limits Continuity And Differentiability Question 38

Question: The function $ f(x)=\sin ({\log _{e}}| x |),x\ne 0 $ , and 1 if $ x=0 $

Options:

A) Is continuous at $ x=0 $

B) Has removable discontinuity at $ x=0 $

C) Has jump discontinuity at $ x=0 $

D) Has oscillating discontinuity at $ x=0 $

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Answer:

Correct Answer: D

Solution:

We have $ \underset{x\to {0^{-}}}{\mathop{\lim }}f(x)=\underset{h\to 0}{\mathop{\lim }}\sin ({\log _{e}}| -h |) $

$ =\underset{h\to 0}{\mathop{\lim }}\sin ({\log _{e}}h) $ Which does not exist but lies between -1 and 1.

Similarly, $ \underset{x\to {0^{+}}}{\mathop{\lim }}f(x) $ lies between -1 and 1 but cannot be determined.