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\(\int \frac{\sec^{2}(\sqrt{2x + 5})}{\sqrt{2x + 5}}dx\)=

  • A.2 tan \((\sqrt{2x + 5}) + C\)
  • B.\(\frac{1}{2}\tan(\sqrt{2x + 5}) + C\)
  • C.tan \((2x + 5) + C\)
  • D.tan \((\sqrt{2x + 5}) + C\)
  • E.2 tan \((2x + 5) + C\)

Answer: D

The integral is \(\tan(\sqrt{2x + 5}) + C\).

Put \(u = \sqrt{2x + 5}\); then \(du = \frac{dx}{\sqrt{2x + 5}}\), exactly the rest of the integrand:

\[ \int\sec^{2}u\,du = \tan u + C = \tan\sqrt{2x + 5} + C \]

The factors 2 and \(\frac{1}{2}\) cancel inside \(du\), so the options with 2 or \(\frac{1}{2}\) in front are wrong, and those in \(\tan(2x + 5)\) lose the square root.

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