Derivative of arcsec(sqrt(x))

1. Dec 13, 2005

gr3g1

Hmmm, I dont seem to get it..

y' of arcsecx is : (1/x * sqrt(x^2 - 1))

im looking for arcsec(sqrt(x))

So I get (1/(sqrt(x)sqrt(x-1)) * 1/2sqrt(x))

Thats not the answer in the book :(

2. Dec 13, 2005

Physics Monkey

3. Dec 13, 2005

gr3g1

The answer given is : 1 / (2x * sqrt(x-1))

4. Dec 13, 2005

Physics Monkey

Edit: At least I think it is, unless I'm misinterpreting your answer.

Last edited: Dec 13, 2005
5. Dec 13, 2005

gr3g1

Hmmm, I dont see it.. and i substitued X by a number, and it gives me 2 different answers

6. Dec 13, 2005

Physics Monkey

Is your answer $$\frac{1}{\sqrt{x}\sqrt{x - 1}}\frac{1}{2 \sqrt{x}}$$ or something else?

7. Dec 13, 2005

gr3g1

8. Dec 13, 2005

Physics Monkey

Well, it is the same then. Just combine the two square roots of x to obtain
$$\frac{1}{\sqrt{x}\sqrt{x - 1}}\frac{1}{2 \sqrt{x}} = \frac{1}{2 x \sqrt{x - 1}}.$$

9. Dec 13, 2005

gr3g1

Ahh!!!! Thanks so much!