$\int \frac{3-x^2}{1-2 x+x^2} e^x d x=e^x f(x)+c \Rightarrow f(x)$

$\int \frac{3-x^2}{1-2 x+x^2} e^x d x=e^x f(x)+c \Rightarrow f(x)$
  1. $\frac{1+x}{1-x}$
  2. $\frac{1-x}{1+x}$
  3. $\frac{1+x}{x-1}$
  4. $\frac{x-1}{1+x}$

Solution


Let $\begin{aligned} I & =\int \frac{3-x^2}{1-2 x+x^2} e^x d x \\ & =\int \frac{3-x^2}{(1-x)^2} e^x d x \\ & =\int\left(\frac{2}{(1-x)^2}+\frac{1+x}{1-x}\right) e^x d x\end{aligned}$
From Eqs. (i) and (ii), we get $ \begin{aligned} & e^x\left(\frac{1+x}{1-x}\right)+c=e^x f(x)+c \\ & \Rightarrow \quad f(x)=\frac{1+x}{1-x} \\ & \end{aligned} $

Asked in: AP EAMCET 2004

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