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Regional Olympiad - FBH 2016 Grade 12 Problem 1

Source: Regional Olympiad - Federation of Bosnia and Herzegovina 2016

September 22, 2018
limitalgebraSequence

Problem Statement

Let a1=1a_1=1 and an+1=an+12ana_{n+1}=a_{n}+\frac{1}{2a_n} for n1n \geq 1. Prove that a)a) nan2<n+n3n \leq a_n^2 < n + \sqrt[3]{n} b)b) limn(ann)=0\lim_{n\to\infty} (a_n-\sqrt{n})=0