Math Is Fun Forum

666 bro

Member

From: Flatland

Registered: 2019-04-26

Posts: 706

Limits

How could we derive properties of limits using definition of limits and why does δ  =(ε/2) for every general cases?

Last edited by 666 bro (2020-03-28 17:09:05)

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"An equation for me has no meaning, unless it expresses a thought of God"- Srinivasa ramanujan

Bob

Administrator

Registered: 2010-06-20

Posts: 10,617

Re: Limits

Sorry, don't understand what is wanted here.  Please give the context for this.  Maybe the lines of working before and after the point where you're not understanding.

Bob

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Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

666 bro

Member

From: Flatland

Registered: 2019-04-26

Posts: 706

Re: Limits

I mean Epsilon -Delta defintion of limits when both (δ , ε) >0  how could we prove  |f(x)-L|< ε and |x-c|<δ?

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"An equation for me has no meaning, unless it expresses a thought of God"- Srinivasa ramanujan

Bob

Administrator

Registered: 2010-06-20

Posts: 10,617

Re: Limits

Sorry.  Still insufficient detail.  What is f(x)? where did L and c come from?

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Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

666 bro

Member

From: Flatland

Registered: 2019-04-26

Posts: 706

Re: Limits

https://youtu.be/w70af5Ou70M    explain?

Last edited by 666 bro (2020-03-28 22:24:09)

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"An equation for me has no meaning, unless it expresses a thought of God"- Srinivasa ramanujan

666 bro

Member

From: Flatland

Registered: 2019-04-26

Posts: 706

Re: Limits

How could we derive Addition property of limit ?

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"An equation for me has no meaning, unless it expresses a thought of God"- Srinivasa ramanujan

Bob

Administrator

Registered: 2010-06-20

Posts: 10,617

Re: Limits

hi 666 bro

Thanks for that link to U Tube.  Now I understand your difficulty. 

Teacher's advice to Khan academy:

(1) Make sure your mic volume is set correctly.  Even on 100% volume I could barely hear the speaker.
(2) Plan your 'board' layout in advance so you don't have wobbly lines and have to rub out bits because they won't fit.
(3) Use different colours but only those that have a decent contrast with the black background.  Yellow is excellent; purple is very poor and barely readable.  Have printed text not handwritten notes so that we don't have to struggle reading your writing.

Sorry 666 bro but I felt I needed to get that off my chest.  No wonder you are struggling with this.  It's great that the Academy do this for free but they could learn a lot from MIF.  I suggest you look instead at this page:

https://www.mathsisfun.com/calculus/limits-formal.html

Compare the two and you'll see why I think MIF is such a brilliant resource.

Hope that helps,

Bob

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Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob