# Math Help - Find the derivative using the definition only!

1. ## Find the derivative using the definition only!

How would you show that the derivative of $f(x) = \frac{1}{\sqrt{x}}$ is equal to $\frac{1}{2\sqrt{x^3}}$ for $x>0$ , using the definition of a derivative??

I started and got lost in the calculation...

$| \frac{\frac{1}{\sqrt{x}}-\frac{1}{\sqrt{c}}}{x-c} + \frac{1}{2\sqrt{c^3}} |$ and show I can make it less than $\epsilon$ , which is just the definition
I know I have $|x-c|<\delta$ to play with... can anyone help me out? this is due tomorrow so the more you can give me the better lol thanks