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AP EAMCET · Maths · Continuity and Differentiability

Which of the following is differentiable at \(x=0 ?\)

  1. A \(f(x)=\cos |x|+|x|\)
  2. B \(f(x)=\sin |x|+|x|\)
  3. C \(f(x)=\cos |x|-|x|\)
  4. D \(f(x)=\sin |x|-|x|\)
Verified Solution

Answer & Solution

Correct Answer

(D) \(f(x)=\sin |x|-|x|\)

Step-by-step Solution

Detailed explanation

At \(x=0\), RHD \(\sin |x|-|x|=\lim _{h \rightarrow 0} \frac{(\sin |h|-|h|-(0)}{h}\) \(\begin{aligned} & =\lim _{h \rightarrow 0}\left(\frac{\sin h}{h}-1\right) \\ & =1-1=0\end{aligned}\) LHD of \(\sin |x|-|x|=\lim _{h \rightarrow 0} \frac{(\sin |-h|-|-h|)}{-h}=0\)…