There is a mistake in your limit:
Do you now see why the result follows?
I'm getting ready for my first semester of Calculus and I'm a big dork so I'm actually interested in the subject.
Anyway I have a quick question: when differentiating I was taught by my trusty textbook to multiply by the conjugate using the difference quotient and so then after several calculations you end up with:
THEN for some reason you can get rid of the "h" in and you're left with .
Now I get how to do everything just fine, I just want to know why the "h" can just go away like that.
Thanks for the help!