Hi,

I am trying some revision for my maths test and I have to use hyperbolic functions to evaluate this integral.

$\displaystyle

\int {\frac{3x}{\sqrt{{x^4-9}}}dx }

$

I am having trouble with the substitution. I tried letting

$\displaystyle

x^2 = 3cosh(u)

$

But I still cant manage to find a solution. I suspect something nice is spose to happen with the 3x on the top of the integral but not sure how. Any help would be greatly appreciated.

Thanks

Elbarto