(1-1/n)^n^2

5 min read Jun 16, 2024
(1-1/n)^n^2

Exploring the Limit of (1 - 1/n)^n^2

The expression (1 - 1/n)^n^2 is a fascinating mathematical concept that reveals a surprising and important result in calculus. Let's delve into its behavior and significance.

Understanding the Expression

At first glance, the expression might seem complicated. However, breaking it down helps us understand its essence:

  • (1 - 1/n): This represents a fraction slightly less than 1, where 'n' is any positive integer. As 'n' grows larger, this fraction approaches 1.
  • n^2: This represents the square of 'n'. It increases much faster than 'n' itself.

Essentially, we're taking a fraction slightly less than 1 and raising it to a very large power. The question is: what happens to the result as 'n' approaches infinity?

The Limit as n Approaches Infinity

Surprisingly, the limit of (1 - 1/n)^n^2 as n approaches infinity is 1/e (where 'e' is Euler's number, approximately 2.71828).

This result is not immediately obvious. The expression appears to involve an exponent that grows unboundedly, leading one to think the result might also approach infinity. However, the decreasing base value (1 - 1/n) counteracts this, ultimately leading to a finite limit.

Proving the Limit

The proof involves using the following steps:

  1. Rewriting the Expression: The expression can be rewritten as: (1 - 1/n)^n^2 = [(1 - 1/n)^n]^n
  2. Recognizing a Familiar Limit: The expression inside the brackets [(1 - 1/n)^n] is the well-known limit that defines 'e', the base of the natural logarithm: lim (n→∞) (1 - 1/n)^n = e
  3. Applying the Limit: Since we know the limit inside the brackets, we can substitute it into the expression: lim (n→∞) [(1 - 1/n)^n]^n = e^n
  4. Final Limit: Now we need to evaluate the limit of e^n as n approaches infinity. This limit diverges to infinity. However, the original expression has an additional 'n' in the exponent: lim (n→∞) (e^n)^(-1) = e^(-∞) = 1/e

Therefore, we have proven that the limit of (1 - 1/n)^n^2 as n approaches infinity is 1/e.

Significance of the Limit

This limit holds profound importance in various fields, including:

  • Calculus: It is used in the derivation of important formulas and results in calculus, particularly related to derivatives and integrals.
  • Probability and Statistics: The limit appears in probability distributions like the Poisson distribution, which is used to model events occurring randomly over time or space.
  • Physics: The limit finds applications in physical phenomena like radioactive decay and the behavior of gases.

Conclusion

The seemingly complex expression (1 - 1/n)^n^2 reveals a fascinating limit, 1/e, with significant implications across different areas of mathematics and science. Its exploration highlights the beauty and power of mathematical concepts and their ability to unravel complex patterns and relationships in the world around us.

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