$\int\left(\frac{x+2}{x+4}\right)^2 \cdot e^x d x=$

$\int\left(\frac{x+2}{x+4}\right)^2 \cdot e^x d x=$
  1. $\mathrm{e}^x\left(\frac{x}{x+4}\right)+\mathrm{c}$, where c is a constant of integration.
  2. $\mathrm{e}^x\left(\frac{x+2}{x+4}\right)+\mathrm{c}$, where c is a constant of integration.
  3. $\mathrm{e}^x\left(\frac{x-2}{x+4}\right)+\mathrm{c}$, where c is a constant of integration.
  4. $\mathrm{e}^x\left(\frac{2 x}{x+4}\right)+\mathrm{c}$, where c is a constant of integration.

Solution

$\begin{aligned} & \mathrm{I}=\int\left(\frac{x+2}{x+4}\right)^2 \mathrm{e}^x \mathrm{~d} x \\ &=\int\left(\frac{x^2+4 x+4}{(x+4)^2}\right) \mathrm{e}^x \mathrm{~d} x \\ &=\int \mathrm{e}^x\left[\frac{x(x+4)}{(x+4)^2}+\frac{4}{(x+4)^2}\right] \mathrm{d} x \\ &=\int \mathrm{e}^x\left[\frac{x}{(x+4)}+\frac{4}{(x+4)^2}\right] \mathrm{d} x \\ &=\mathrm{e}^x\left(\frac{x}{x+4}\right)+\mathrm{c} \\ & \quad \cdots\left[\int\left(\mathrm{f}(x)+\mathrm{f}^{\prime}(x) \mathrm{e}^x \mathrm{~d} x=\mathrm{e}^x \mathrm{f}(x)+\mathrm{c}\right)\right]\end{aligned}$

Asked in: MHT CET 2024 (02 May Shift 1)

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