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m Reverted 1 edit by 2001:D08:1392:C2B0:A5A8:CB1D:928B:84F6 (talk) to last revision by PicoMath |
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: <math>f : \Z \to \N,</math> defined by:
: <math>f(n) = m</math> if, and only if, <math>m^2 = n,</math> <math>m \in \N, n \in \Z,</math>
then <math>f(n)</math> is only defined if <math>n</math> is a [[Square number|perfect square]] (that is, <math>0, 1, 4, 9, 16, \ldots</math>). So <math>f(25) = 5</math> but <math>f(26)</math> is undefined.
== Basic concepts ==
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