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Mathematics 14 Online
OpenStudy (kg1975):

Ms. Vic's Calculus Class (9:00) Join If Wanted! Medal's Will Be Given

OpenStudy (kg1975):

Session on Limits

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Message Me If You Have A Question

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Class Starts At 9:00

OpenStudy (kg1975):

Ok Welcome To My Calculus Class Many People Have Been Having Trouble With.

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If You Have A Question. or know the answer just type it out ok

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So, todays lesson is on limits. You have seen enough limits to be ready for a definition. It is true that we have survived this far without one, and we could continue. But this seems a reasonable time to define limits more carefully

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The goal is to achieve rigor without rigor mortis. First you should know that limits of Ay/Ax are by no means the only limits in mathematics.

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Here are five completely different examples. They involve n + a,not Ax +0: 1. a, = (n -3)/(n + 3) (for large n, ignore the 3's and find a, + 1) 2. a, =)a,-, + 4 (start with any a, and always a, +8) 3. an=probability of living to year n (unfortunately an +0) 4. a, = fraction of zeros among the first n digits of n (an+h?) 5. a, = .4, a2 = .49, a, = .493, .... No matter what the remaining decimals are, the a's converge to a limit. Possibly a, +.493000 . . .,but not likely.

OpenStudy (kg1975):

The problem is to say what the limit symbol + really means. A good starting point is to ask about convergence to zero. When does a sequence of positive numbers approach zero? What does it mean to write an +O? The numbers a,, a,, a,, ..., must become "small," but that is too vague. We will propose four definitions of convergence to zero, and I hope the right one will be clear.

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All the numbers a, are below 10- lo. That may be enough for practical purposes, but it certainly doesn't make the a, approach zero. 2. The sequence is getting closer to zero-each a,, is smaller than the preceding a,. This test is met by 1.1, 1.01, 1.001, ... which converges to 1 instead of 0. 3. For any small number you think of, at least one of the an's is smaller. That pushes something toward zero, but not necessarily the whole sequence. The condition would be satisfied by 1, ),1, f, 1, i,. . . ,which does not approach zero. 4. For any small number you think of, the an's eventually go below that number and stay below.

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Does Anyone Know The True definition for limits out of these 4 choices?

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anyone?

OpenStudy (kg1975):

yes! that is correct!

OpenStudy (kg1975):

I want to repeat that. To test for convergence to zero, start with a small number- say 10-lo. The an's must go below that number. They may come back up and go below again-the first million terms make absolutely no difference. Neither do the next billion, but eventually all terms must go below lo-''. After waiting longer (possibly a lot longer), all terms drop below The tail end of the sequence decides everything

OpenStudy (kg1975):

@andrejrusa12

OpenStudy (kg1975):

Does this sequence \[10^{-3} , 10^{-2}, 10^{-6},10^{-5},10^{-9},10^{-8}\] aproach 0?

OpenStudy (kg1975):

anyone?

OpenStudy (kg1975):

The answer is Yes, These up and down numbers eventually stay below any

OpenStudy (kg1975):

ok does Does \[10^{-4 }, 10^{-4},10^{-4},10^{-6},10^{-8},10^{-10}\], ... approach zero?

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anyone have a answer?

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best guess?

OpenStudy (kg1975):

No it does not reach 0

OpenStudy (kg1975):

This sequence goes below but does not stay below

OpenStudy (kg1975):

Any questions???

OpenStudy (kg1975):

if there are no questions this class is done i will stay in for a while and answer any questions u might have

OpenStudy (kg1975):

this class is now done and im closing the session

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