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MHT CET · Maths · Indefinite Integration

\(\int\left[\frac{(1+\log x)}{\cos ^{2}(x \log x)}\right] d x=\)

  1. A \(\sin (x \log x)+c\)
  2. B \(\sin ^{2}(x \log x)+c\)
  3. C \(\log (x \log x)+c\)
  4. D \(\tan (x \log x)+c\)
Verified Solution

Answer & Solution

Correct Answer

(D) \(\tan (x \log x)+c\)

Step-by-step Solution

Detailed explanation

\(I=\int \frac{(1+\log x)}{\cos ^{2}(x \log x)} d x\)
Put \(x \log x=t \Rightarrow\left[x \cdot \frac{1}{x}+\log x(1)\right] d x=d t \Rightarrow\) \((1-\log x) d x=d t\)
\(1=\int \frac{1}{\cos ^{2} t} d t=\int \sec ^{2} t d t=\tan t+c\)
\(=\tan (x \log x)-c\)