MathDB
Irrationals and powers

Source: 2016 Nigerian Senior MO Round 2

November 16, 2022
inductionIrrational numbersalgebra

Problem Statement

Prove that (2+3)2n+(23)2n(2+\sqrt{3})^{2n}+(2-\sqrt{3})^{2n} is an even integer and that (2+3)2n(23)2n=w3(2+\sqrt{3})^{2n}-(2-\sqrt{3})^{2n}=w\sqrt{3} for some positive integer ww, for all integers n1n \geq 1.