## anonymous 4 years ago Calculus II - Trig Integration Hello, I am stuck on getting the following problem setup; Evaluate the integral; $\int\limits(1/(x*\sqrt(x^8-9) dx$ So I know this is in the form $\int\limits du/u*\sqrt(u^2 - a^2) = (1/a) \sec^-1(|u/a|) + C$ But I am not sure how to get that X and X^8 out of there. I know if the X was X^4 then X^8 would be (X^4)^2 but I am not really sure what to do. Any help starting this problem out would be great!

1. anonymous

Is it as simple as saying U = X^4 and then solving for U?

2. amistre64

looks to be a secant type?

3. amistre64

yeah, if i recall correctly