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AP EAMCET · Maths · Indefinite Integration

\(\int\left(1+e^{-x}\right)^{-1} d x=\)

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

Answer & Solution

Correct Answer

(B) \(\log \left(1+e^x\right)+c\)

Step-by-step Solution

Detailed explanation

\(I=\int\left(1+e^{-x}\right)^{-1} d x=\int \frac{e^x}{e^x+1} d x\) Put \(e^x+1=t \Rightarrow e^x d x=d t\) So, \(I=\int \frac{d t}{t}=\log _e|t|+C=\log _e\left(1+e^x\right)+C\)