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Question: Answered & Verified by Expert
$\int \frac{3-x^2}{1-2 x+x^2} e^x d x=e^x f(x)+c \Rightarrow f(x)$
MathematicsIndefinite IntegrationJEE Main
Options:
  • A $\frac{1+x}{1-x}$
  • B $\frac{1-x}{1+x}$
  • C $\frac{1+x}{x-1}$
  • D $\frac{x-1}{1+x}$
Solution:
1384 Upvotes Verified Answer
The correct answer is: $\frac{1+x}{1-x}$


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
$$
\begin{aligned}
& e^x\left(\frac{1+x}{1-x}\right)+c=e^x f(x)+c \\
& \Rightarrow \quad f(x)=\frac{1+x}{1-x} \\
&
\end{aligned}
$$

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