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| | The concept of the '''limit''' is the cornerstone of [[calculus]], [[analysis]], and [[topology]]. At the simplest intuitive level, the limit of a function at a point is the value that the function "approaches" as its argument "approaches" that point. As we will see, that is an unsatisfactory definition, and a much more careful definition is required. | | The concept of the '''limit''' is the cornerstone of [[calculus]], [[analysis]], and [[topology]]. At the simplest intuitive level, the limit of a function at a point is the value that the function "approaches" as its argument "approaches" that point. As we will see, that is an unsatisfactory definition, and a much more careful definition is required. |
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| − | ==Limit of a Sequence==
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| − | Let <math>(a_n)_{n\in N} = (a_1, a_2, a_3, ...)</math> be a [[sequence]] of [[real number]]s. We say that this sequence has a limit <math>a</math>, i.e.,
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| − | <math>
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| − | \lim_{n\to \infty} = a,
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| − | </math>
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| − | if for any <math>\varepsilon > 0</math>, there exists a number <math>N</math>, such that
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| − | <math>
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| − | |a_n - a| < \varepsilon</math> for every <math>n > N</math>. Intuitively, this means that if you take an [[interval]] as small as you like, [[center]]ed at the limit point, then most - i.e., all but a finite number - of the points of the sequence are in that interval.
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| | ==Limit of a Function== | | ==Limit of a Function== |
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| | We still haven't proved that the limit is actually 1. We just gave some accurate calculations strongly suggesting that it is. In fact it is, and the proof requires a few theorems about limits, [continuous function]]s, and the [[exponential]] and [[natural logarithm]] functions. | | We still haven't proved that the limit is actually 1. We just gave some accurate calculations strongly suggesting that it is. In fact it is, and the proof requires a few theorems about limits, [continuous function]]s, and the [[exponential]] and [[natural logarithm]] functions. |
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| | + | ==Limit of a Sequence== |
| | + | Let <math>(a_n)_{n\in N} = (a_1, a_2, a_3, ...)</math> be a [[sequence]] of [[real number]]s. We say that this sequence has a limit <math>a</math>, i.e., |
| | + | <math> |
| | + | \lim_{n\to \infty} = a, |
| | + | </math> |
| | + | if for any <math>\varepsilon > 0</math>, there exists a number <math>N</math>, such that |
| | + | <math> |
| | + | |a_n - a| < \varepsilon</math> for every <math>n > N</math>. Intuitively, this means that if you take an [[interval]] as small as you like, [[center]]ed at the limit point, then most - i.e., all but a finite number - of the points of the sequence are in that interval. |
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| | [[category:mathematics]] | | [[category:mathematics]] |