# Trig Substitution

• Apr 20th 2010, 05:45 PM
x5pyd3rx
Trig Substitution
The problem us integrate : $\frac{1}{x \sqrt{x^2+25}}dx$

I worked it out to here
$

\frac{5secT}{5tanT} dT$

1. Is this right so far and 2. Im a little confused on how to proceed from there.
• Apr 20th 2010, 05:57 PM
Well, ASSUMING what you did up to there was right then use...

$\sec(x) = \frac{1}{\cos(x)}$

and

$\tan(x) = \frac{\sin(x)}{\cos(x)}$
• Apr 20th 2010, 06:01 PM
TKHunny
Good start. Extra factor of 5 in the numerator.
• Apr 20th 2010, 06:18 PM
x5pyd3rx
Thats kind of what i thought so it should be $\frac{secT}{5tanT}dT$
• Apr 21st 2010, 03:22 AM
Thats kind of what i thought so it should be $\frac{secT}{5tanT}dT$