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AP EAMCET · Maths · Differentiation

If \(y=\log (\cosh x)\) then \(\frac{d^2 y}{d x^2}=\)

  1. A \(\operatorname{sech}^2 x\)
  2. B \(-\operatorname{sech}^2 x\)
  3. C \(\sinh x\)
  4. D \(-\sinh x\)
Verified Solution

Answer & Solution

Correct Answer

(A) \(\operatorname{sech}^2 x\)

Step-by-step Solution

Detailed explanation

\(y=\log (\cos \mathrm{h} x)\) Differentiating w.r.t. ' \(x\) ' on both sides \[ \begin{aligned} & \frac{d y}{d x}=\frac{1}{\cosh x}(\sinh x) \\ & \frac{d y}{d x}=\tanh x \end{aligned} \] Again differentiating w.r.t. ' \(x\) ' on both sides…