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Romanian National Olympiad 2018 - Grade 12 - problem 2

Source: Romania NMO - 2018

April 7, 2018
functioncalculusintegrationreal analysiscollege contests

Problem Statement

Let F\mathcal{F} be the set of continuous functions f:RRf: \mathbb{R} \to \mathbb{R} such that ef(x)+f(x)x+1,xRe^{f(x)}+f(x) \geq x+1, \: \forall x \in \mathbb{R} For fF,f \in \mathcal{F}, let I(f)=0ef(x)dxI(f)=\int_0^ef(x) dx Determine minfFI(f).\min_{f \in \mathcal{F}}I(f).
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