1. Originally Posted by CaptainBlack
try $\tan(u)=x$

RonL
That is exactly what I did.

2. Originally Posted by ThePerfectHacker
That is exactly what I did.
Some kind of glitch, when I posted I could not see any replies

In fact a mental glitch, the replies were on the next page

RonL

3. $\int\frac{dx}{x\sqrt{x^2-1}}$
using substitution $x=\frac{1}{t}$ in order to find integral

i got that $dx=-\frac{dt}{t^2}$

if i substitute it what should i do with denominator, especially with sqrt ?

oh i hate it. i am going to have a test tomorrow