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