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Prove this.

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May 2, 2020
algebranumber theory

Problem Statement

Let α\alpha and β\beta be irrational numbers with the property that 1α+1β=1\frac{1}{\alpha} +\frac{1}{\beta}=1 Let{an}\{a_n\} and {bn}\{b_n\} be the sequences given by an=nαa_n= \lfloor n\alpha \rfloor and bn=nβb_n= \lfloor n\beta \rfloor respectively. Prove that the sequences {an}\{ a_n\} and {bn}\{ b_n \} has no term in common and cover all the natural numbers.
I know this theorem from long ago, but forgot the proof of it. Can anybody help me with this?