\int \frac{\sec ^{2}(\log x)}{x} d x= ?
(A) \tan (\log x)+k
(B) -\tan (\log x)+k
(C) \cot (\log x)+k
(D) -\cot (\log x)+k
\int \frac{\sec ^{2}(\log x)}{x} d x= ?
(A) \tan (\log x)+k
(B) -\tan (\log x)+k
(C) \cot (\log x)+k
(D) -\cot (\log x)+k

Correct option is (A) \tan (\log x)+k
Let I=\int \frac{\sec ^{2}(\log x)}{x} d x
Put \log x=t \Rightarrow \frac{1}{x} d x=d t

    \[\therefore \int \sec ^{2} t d t=\tan t+c=\tan (\log x)+c\]