Integrating by Substitution: Solving Integrals with Square Roots

[futb0l]

Can anyone help me with the following integrals (integrate by substitution)?

<br /> \int{\frac{dx}{\sqrt{x^2 - 4}}}<br />

<br /> \int{\frac{dx}{\sqrt{x^2 + 4}}}<br />

I have no idea whatsoever on how to do it.

 

[courtrigrad]

\int{\frac{dx}{\sqrt{x^2 - 4}}}. Use the substitution x = 2\sec \theta

<br /> \int{\frac{dx}{\sqrt{x^2 + 4}}}<br /> Use the substitution x = 2\tan \theta

 

[futb0l]

Right, thanks a lot :D