- #1
jaci55555
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Homework Statement
Prove that
a^3 - a is a multiple of 3
a^5 - a is a multiple of 5
Generalise … to a^n - a a multiple of n
Homework Equations
The Attempt at a Solution
a^3 - a = a(a^2 - 1) = a(a+1)(a-1)
thus three consecutive numbers are multiplied. if three numbers are consecutive >0, one is a multiple of three and thus the product a multiple of three
a^5 - a = a(a^4-1) = a(a^2+1)(a^2-1) = a(a+1)(a-1)(a^2+1)
if i put a =1 then i get 5... but?
and how do i generalize?
i suspect there is just a small thing I'm missing