Math Is Fun Forum

Au101

Member

Registered: 2010-12-01

Posts: 353

Introductory Limits

Hello everyone,

So, I've been away from maths for a while and - since I've missed it - I decided I wanted to brush up on my calculus a bit, which has deteriorated rather a lot. Anyway, I've been reading through an old textbook of mine and I've come across the line:

I don't know if I'm just missing an obvious fact since everything's a bit slow and clunky for me these days, but I can't see where the second line comes from and was hoping someone might be able to explain it to me. Thanks

anonimnystefy

Real Member

From: Harlan's World

Registered: 2011-05-23

Posts: 16,049

Re: Introductory Limits

Hi Au101

It is a well-known identity:

---

“Here lies the reader who will never open this book. He is forever dead.
“Taking a new step, uttering a new word, is what people fear most.” ― Fyodor Dostoyevsky, Crime and Punishment
The knowledge of some things as a function of age is a delta function.

Au101

Member

Registered: 2010-12-01

Posts: 353

Re: Introductory Limits

Ahhh thank you anonimnystefy, now I see, because of course

And then all the terms in between cancel That's a great help

Last edited by Au101 (2013-06-05 07:03:46)

anonimnystefy

Real Member

From: Harlan's World

Registered: 2011-05-23

Posts: 16,049

Re: Introductory Limits

That is correct! You are welcome!

If there's anything else, just ask.

---

“Here lies the reader who will never open this book. He is forever dead.
“Taking a new step, uttering a new word, is what people fear most.” ― Fyodor Dostoyevsky, Crime and Punishment
The knowledge of some things as a function of age is a delta function.