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KCET · Maths · Indefinite Integration

The value of \(\int \frac{x^{2}+1}{x^{2}-1} d x\) is

  1. A \(\log \left(\frac{x-1}{x+1}\right)+c\)
  2. B \(\log \left(\frac{x+1}{x-1}\right)+c\)
  3. C \(x+\log \left(\frac{x-1}{x+1}\right)+c\)
  4. D \(\log \left(x^{2}-1\right)+c\)
Verified Solution

Answer & Solution

Correct Answer

(C) \(x+\log \left(\frac{x-1}{x+1}\right)+c\)

Step-by-step Solution

Detailed explanation

Let \(I=\int \frac{x^{2}+1}{x^{2}-1} d x=\int \frac{x^{2}+1-1+1}{x^{2}-1} d x\)
\[
\begin{aligned}
&\Rightarrow I=\int \frac{x^{2}-1}{x^{2}-1} d x+\int \frac{2}{x^{2}-1} d x \\
&\Rightarrow I=\int 1 d x+2 \int \frac{1}{x^{2}-1} d x \\
&\Rightarrow I=x+2 \cdot \frac{1}{2} \log \left(\frac{x-1}{x+1}\right)+c \\
&\Rightarrow I=x+\log \left(\frac{x-1}{x+1}\right)+c
\end{aligned}
\]