use the definition of the derivative to f(x)

[lrhodes]

f(x)=sqrt(x-2)

f(x)=lim f(x+h)-f(x)/h
h->0

I am kind of confused what replaces what, this is what I came up with:

sqrt((x-2)+h)-(srqt(x-2))/h

so then I have to multiply to get rid of the sqrt

sqrt((x-2)+h)-(srqt(x-2))*sqrt((x-2)+h)-(srqt(x-2))/h/h*sqrt((x-2)+h)-(srqt(x-2))/h

and now im lost

 

[tkhunny]

f(x)=lim f(x+h)-f(x)/h
h->0

This is quite bad notation. Please correct it and you will be less confused.

Ponder this

\(\displaystyle \frac{\sqrt{a} - \sqrt{b}}{12}\cdot\frac{\sqrt{a} + \sqrt{b}}{\sqrt{a} + \sqrt{b}}\)

Think about the "conjugate" and the "difference of squares".