Hey all,

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!