# Having trouble with a Calculs Integration

• Aug 2nd 2013, 12:38 AM
Memorystack
Having trouble with a Calculs Integration
The integration is [dx / (x Sqrt[1 - x])

Seems pretty simple but the question specify to not use the Tanh integration formula...

Now i'm stuck if my calculation are correct. Using the Pythagore i get to a point where i integrate Sec (theta)

and stuck... got Ln ¦ sec (theta) + Tan (theta) ¦ + c... then nothing i can't find the right answer that fit with the real anwer that is

If anyone could tell me if i made a mistake or send me in the right direction would be great

Log[1 - Sqrt[1 - x]] - Log[1 + Sqrt[1 - x]]
• Aug 2nd 2013, 01:18 AM
MarkFL
Re: Having trouble with a Calculs Integration
If you observe that:

$\displaystyle x=(1+\sqrt{1-x})(1-\sqrt{1-x})$

and then make the substitution:

$\displaystyle u^2=1-x\,\therefore\,dx=-2u\,du$

you get:

$\displaystyle 2\int\frac{du}{u^2-1}$

and now factor the denominator, and use partial fractions...
• Aug 2nd 2013, 01:58 AM
Memorystack
Re: Having trouble with a Calculs Integration
Wow fast answer and right answer just did the whole thing it work very well!!!

Sorry if the problem was to easy I tought I'd put more of a challenge!

Thanks MarkFl