ExamBro
ExamBro
MHT CET · Maths · Indefinite Integration

\(\int \frac{1+2 e^{-x}}{1-2 e^{-x}} d x=\)

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

Answer & Solution

Correct Answer

(D) \(x+2\log \left(1-2 e^{-x}\right)+\mathrm{c}\)

Step-by-step Solution

Detailed explanation

(B)
Let \(1 =\int \frac{1-2 e^{-x}}{1-2 e^{-1}} \)
\(=\int \frac{1-2 e^{-x}+4 e^{-x}}{1-2 e^{-1}} d x=\int \frac{1-2 e^{-x}}{1-2 e^{-1}} d x+4 \int \frac{e^{-x}}{1-2 e^{-x}} d x \)
\(=\int d x+\frac{4}{2} \int \frac{2 e^{-x}}{1-2 e^{-x}} d x=x-2 \cdot \log 1-2 e^{-1}-c\)