How to integrate int (x^2 + 4)^(-1/2) dx Is it a substitution?

1. Jun 20, 2005

gordda

I need help antidiffing this equation:
(x^2+4)^(-1/2)

i have tried subbing u=x^2+4 i have tried subbing u= (x^2+4)^(-1/2).
i have tried making x the subject. even tried to use partial fraction, with no avail, because i could not figure out how to use partially factorize it.
If anyone could lead me towards the right answer.
Thanks.

2. Jun 20, 2005

saltydog

Whenever you have an integrand that looks like the Pathagoras theorem, use trig substitutions. You know, draw a right triangle with theta in it. Then the hypotneuse is the radical, one side is 2, the other is x right. Follow through: What would the tan(theta) be?