Math Is Fun Forum

sami4

Member

Registered: 2010-11-30

Posts: 7

Calculus: Limit

What happens to the limit of F(x) as x approaches to 1:

[(x^2)-x-2]/[(x^2)-1]

L'hopital rule can not be applied in this case, since it is not 0/0 , and if we simply , we get (x-2)/(x-1), which doesn't work as well
I'm leaning towards that this limit does not exist. I'd be grateful if anyone can help me out

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Calculus: Limit

Hi sami4;

You are on the right track. Try examining it when x = .9, .99, .999 ...
and then when x = 1.1,1.01,1.001...

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

sami4

Member

Registered: 2010-11-30

Posts: 7

Re: Calculus: Limit

Thank you for your quick reply.
As X approaches to 1 from above, the limit goes to + infinity and as X approaches to 1 from below, the limit goes to - infinity. Therefore it does not exist as X -> 1

Last edited by sami4 (2010-11-30 22:53:07)

123ronnie321

Member

Registered: 2010-09-28

Posts: 128

Re: Calculus: Limit

you are right. the limit does not exist.
draw a graph of (x-2)/(x-1) and you will know better.

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Calculus: Limit

Hi sami4;

Also try this page about half way down:

http://www.mathsisfun.com/calculus/limits.html

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

sami4

Member

Registered: 2010-11-30

Posts: 7

Re: Calculus: Limit

Thank you so much. You have been very helpful

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Calculus: Limit

Hi sami4;

Your welcome and welcome to the forum.

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.