Originally Posted by

**whiteslash** Hi MHF,

There are two questions that are confusing me. I understand the material, but when I was working them out, I would get stuck (with algebra parts) and I do not know how to continue.

a) Find y'' by implicit differentiation.

$\displaystyle \sqrt{x}+\sqrt{y} = 1$

I found y'=$\displaystyle -\sqrt{y} /\sqrt{x}$

(that's supposed to be a fraction)

What is y''?

b) If f$\displaystyle (\theta)$ = cot$\displaystyle (\theta)$, find f'''($\displaystyle \frac{\pi}{6}$)

f'(x) = $\displaystyle csc^2x$

What is f"? f"'?

Thank you very much!