EDB — 0C1

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Exercises

  1. [0C1]Prerequisites:[0BW]. (Dirichlet’s approximation theorem) Given an irrational number \(x\), show that there are infinitely many rationals \(𝛼\) such that we can represent \(𝛼=m/n\) in order to satisfy the relation

    \[ \left| x - \frac m n \right| {\lt} \frac 1{n^ 2}\quad . \]

    Some comments.

    • Note for every fixed \(n≥ 2\) there is at most an \(m\) for which the previous relation holds; but there may not be one.

    • Note that if the relation holds for a rational \(𝛼\), there are only finite choices of representations for which it holds,

    • and certainly it holds for the "canonical" representation with \(n,m\) coprimes.

    Solution 1

    [0C2]

    [2B0]

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Bibliography
Book index
  • theorem, Dirichlet's approximation
  • Dirichlet's approximation theorem
  • rational numbers
  • irrational numbers
  • real numbers
  • polynomial
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