ExamBro
ExamBro
MHT CET · Maths · Indefinite Integration

If \(\mathrm{f}(x)=1+x ; \mathrm{g}(x)=\log x\), then \(\int \mathrm{g}(\mathrm{f}(x)) \mathrm{d} x\) is equal to

  1. A \((1+x) \log (1+x)-x+\mathrm{c}\), (where c is a constant of integration)
  2. B \((1+x) \log x-x+\mathrm{c}\), (where c is a constant of integration)
  3. C \(x \log (1+x)+\mathrm{c}\), (where c is a constant of integration)
  4. D \((1+x) \log (1+x)+x+\mathrm{c}\), (where c is a constant of integration)
Verified Solution

Answer & Solution

Correct Answer

(A) \((1+x) \log (1+x)-x+\mathrm{c}\), (where c is a constant of integration)

Step-by-step Solution

Detailed explanation

\(\begin{aligned} & \int \mathrm{g}(\mathrm{f}(x)) \mathrm{d} x \\ & =\int 1 \times \log (1+x) \mathrm{d} x\end{aligned}\)
\(\begin{aligned} & =x \log (1+x)-\int x \times \frac{1}{(1+x)} \mathrm{d} x+\mathrm{c} \\ & =x \log (1+x)-\left[\int \frac{1+x}{1+x} \mathrm{~d} x-\int \frac{1}{1+x} \mathrm{~d} x\right]+\mathrm{c} \\ & =x \log (1+x)-x+\log (1+x)+\mathrm{c} \\ & =(1+x) \log (1+x)-x+\mathrm{c}\end{aligned}\)
From MHT CET
Explore more questions on app