# Math Help - [SOLVED] complex dirvative first princple

1. ## [SOLVED] complex dirvative first princple

by using first princple

2. Just differentiate it like an ordinary function.

3. Originally Posted by shawsend
Just differentiate it like an ordinary function.
I need to show it from first princple, which i am finding it hard 2 do.

4. You can do the $3z^2$ from the definition right? I'll do the other part:

Let $g(z)=i/z$

then:

$g'(z)=\lim_{\Delta z\to 0} \frac{\frac{i}{z+\Delta z}-\frac{i}{z}}{\Delta z}=\lim_{\Delta z\to 0}\frac{-i\Delta z}{z(z+\Delta z)\Delta z}=\lim_{\Delta z\to 0} \frac{-i}{z(z+\Delta z)}=-\frac{i}{z^2}$

5. THANKS FOR YOUR HELP. i MANAGE TO SOLVE THE PROBLEM AT THE END.