$\begin{aligned} & y=\sin \left(\log \left(x^2+2 x+1\right)\right) \\ & \Rightarrow(x+1)^2 \frac{d^2 y}{d…

$\begin{aligned} & y=\sin \left(\log \left(x^2+2 x+1\right)\right) \\ & \Rightarrow(x+1)^2 \frac{d^2 y}{d x^2}+(x+1) \frac{d y}{d x}=\end{aligned}$
  1. $y$
  2. $-4 y$
  3. $4 y$
  4. $-y$

Solution

(b) Given, $y=\sin \left(\log \left(x^2+2 x+1\right)\right)$ $ \Rightarrow \quad y=\sin [2 \log (x+1)] $ So, $\frac{d y}{d x}=\left[\cos (2 \log (x+1)] \times\left(\frac{2}{x+1}\right)\right.$ $ \Rightarrow \quad(x+1) \frac{d y}{d x}=2 \cos (2(\log (x+1)) $ On differentiating both side with respect to ' $x$ ' $ \begin{aligned} & (x+1) \frac{d^2 y}{d x^2}+\frac{d y}{d x}=-2(\sin (2 \log (1+x)))\left(\frac{2}{x+1}\right) \\ & \Rightarrow \quad(x+1)^2 \frac{d^2 y}{d x^2}+(x+1) \frac{d y}{d x}=-4 y \end{aligned} $

Asked in: AP EAMCET 2018 (22 Apr Shift 2)

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