Answer
$$\sec^{-1}(5x)+c.$$
Work Step by Step
Let $u=5x$, then $du=5dx$ and hence we have
$$\int \frac{dx}{x\sqrt{25x^2-1}}=\int \frac{du}{u\sqrt{u^2-1}}\\
=\sec^{-1}u+c=\sec^{-1}(5x)+c.$$
You can help us out by revising, improving and updating this answer.
Update this answerAfter you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.