Saturday, 28 November 2015

calculus - fractional part of the square of natural number



How can if prove that the sequence :an={n}(fractionalpartofn)=n[n]
is bounded from above by 1?
So far i try induction but its nothing that the assumption can help me for the "step" of the induction so i kind of stuck here.
tnx!




*([x] - the floor function of x)


Answer



The fractional part of a number is, by definition, between 0 and 1. This is because [x], the integer part of x, is defined as




The largest integer nZ such that $n



Therefore, if x[x]>1, then [x]+1 is:





  • smaller than x (because x[x]>1 can be rearanged to x>[x]+1)

  • larger than [x] (by definition, it is larger by 1.



meaning that [x] is not the largest integer satisfying $n

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