Hi all,

Could someone please show me how to integrate:

[ ( 1 + 4kut ) ^1/2 ] / 2kt dt

I've tried everything, maybe I'm just being dim but I can't find a substitution that works and I can't do it by parts. (Doh)

Printable View

- April 22nd 2012, 06:23 PMIvanator27Integration Question
Hi all,

Could someone please show me how to integrate:

[ ( 1 + 4kut ) ^1/2 ] / 2kt dt

I've tried everything, maybe I'm just being dim but I can't find a substitution that works and I can't do it by parts. (Doh) - April 22nd 2012, 07:41 PMProve ItRe: Integration Question
- April 26th 2012, 01:15 AMIvanator27Re: Integration Question
http://latex.codecogs.com/gif.latex?...\sqrt{1+4kut}}

I agree with that, however once:

http://latex.codecogs.com/gif.latex?v=\sqrt{1+4kut}

http://latex.codecogs.com/gif.latex?...qrt{1+4kut}}dt

http://latex.codecogs.com/gif.latex?...+4kut}}{2ku}dv

Which leads me to:

http://latex.codecogs.com/gif.latex?...20\right%20)dv

http://latex.codecogs.com/gif.latex?...frac{v^2}{t}dv

(Thinking) - April 26th 2012, 01:59 AMbiffboyRe: Integration Question
Let z^2=1+4kut SO 2zdz/dt=4ku So zdz/2ku z^2-1=4kut So 2kt=(z^2-1)/u

Integral becomes 1/2k integral of z^2/(z^2-1) Now write z^2/(z^2-1)= 1+1/(z^2-1) and partial fraction 1/(z^2-1) - April 26th 2012, 02:05 AMbiffboyRe: Integration Question
End of my 1st line should have been 2kt=(z^2-1)/2u

- April 26th 2012, 02:24 AMIvanator27Re: Integration Question
http://latex.codecogs.com/gif.latex?...w%202zdz=4kudt

http://latex.codecogs.com/gif.latex?dt=\frac{2z}{4ku}dz

I don't see how this helps me, it leads to:

http://latex.codecogs.com/gif.latex?...frac{z^2}{t}dz

Which is exactly what happens if you let http://latex.codecogs.com/gif.latex?z=\sqrt{1+4kut}

Maybe I'm not understanding exactly what you were saying. - April 26th 2012, 02:46 AMbiffboyRe: Integration Question
It was just an alternative substitution. You now need to write t in terms of z.

- April 26th 2012, 03:12 AMIvanator27Re: Integration Question
Ohhhh! Thanks so much! I have it know. =D

...Thanks again!