Forced to a Half

Problem

A function f ⁣:RRf \colon \mathbb{R} \to \mathbb{R} satisfies, for all real x,y,zx, y, z,

f(xy)+f(xz)2f(x)f(yz)12.f(xy) + f(xz) - 2f(x)f(yz) \geqslant \frac{1}{2}.

Find

1f(1)+2f(2)++2022f(2022),\lfloor 1 \cdot f(1) \rfloor + \lfloor 2 \cdot f(2) \rfloor + \cdots + \lfloor 2022 \cdot f(2022) \rfloor,

where x\lfloor x \rfloor denotes the greatest integer not exceeding xx.

Answer

Solution

Difficulty6/10
Topicsfunctions, Substitution, algebra, Functional Equations

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