MathDB
I 19

Source:

May 25, 2007
floor functionfunctiontrigonometry

Problem Statement

Let a,b,ca, b, c, and dd be real numbers. Suppose that na+nb=nc+nd\lfloor na\rfloor +\lfloor nb\rfloor =\lfloor nc\rfloor +\lfloor nd\rfloor for all positive integers nn. Show that at least one of a+ba+b, aca-c, ada-d is an integer.