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unique division and limit

Source: romanian nmo 2007, grade 12, problem 2

April 15, 2007
integrationcalculusreal analysisreal analysis unsolved

Problem Statement

Let f:[0,1](0,+)f: [0,1]\rightarrow(0,+\infty) be a continuous function. a) Show that for any integer n1n\geq 1, there is a unique division 0=a0<a1<<an=10=a_{0}<a_{1}<\ldots<a_{n}=1 such that akak+1f(x)dx=1n01f(x)dx\int_{a_{k}}^{a_{k+1}}f(x)\, dx=\frac{1}{n}\int_{0}^{1}f(x)\, dx holds for all k=0,1,,n1k=0,1,\ldots,n-1. b) For each nn, consider the aia_{i} above (that depend on nn) and define bn=a1+a2++annb_{n}=\frac{a_{1}+a_{2}+\ldots+a_{n}}{n}. Show that the sequence (bn)(b_{n}) is convergent and compute it's limit.