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JEE Mains · Maths · STD 12 - 7.1 indefinite integral

The value of the integral \(\int_{-1}^2 \log _e\left(x+\sqrt{x^2+1}\right) d x\) is :

  1. A  \(\sqrt{5}-\sqrt{2}+\log _{\mathrm{e}}\left(\frac{9+4 \sqrt{5}}{1+\sqrt{2}}\right)\)
  2. B  \(\sqrt{2}-\sqrt{5}+\log _{\mathrm{e}}\left(\frac{9+4 \sqrt{5}}{1+\sqrt{2}}\right)\)
  3. C \(\sqrt{5}-\sqrt{2}+\log _{\mathrm{e}}\left(\frac{7+4 \sqrt{5}}{1+\sqrt{2}}\right)\)
  4. D  \(\sqrt{2}-\sqrt{5}+\log _{\mathrm{e}}\left(\frac{7+4 \sqrt{5}}{1+\sqrt{2}}\right)\)
Verified Solution

Answer & Solution

Correct Answer

(B)  \(\sqrt{2}-\sqrt{5}+\log _{\mathrm{e}}\left(\frac{9+4 \sqrt{5}}{1+\sqrt{2}}\right)\)

Step-by-step Solution

Detailed explanation

\( I=\int_{-1}^2 1 \log _e\left(x+\sqrt{x^2+1}\right) d x \) \( =x \log _e\left(x+\sqrt{x^2+1}\right)-\int_{-1}^2\left(\frac{1+\frac{x}{\sqrt{x^2+1}}}{x+\sqrt{x^2+1}}\right) d x \) \( =x \log _e\left(x+\sqrt{x^2+1}\right)-\int_{-1}^2 \frac{x}{\sqrt{x^2+1}} d x \)…