\( A = n^5 - n \\
= n.(n^4 - 1) \\
= n.(n^2 + 1)(n^2 - 1) \)
\(= n.(n² + 1)(n - 1)(n + 1\)) (chia hết cho 6, vì chia hết cho 2, 3)
A=n5−n=n.(n4−1)=n.(n2+1)(n2−1)A=n5−n=n.(n4−1)=n.(n2+1)(n2−1)
=n.(n²+1)(n−1)(n+1=n.(n²+1)(n−1)(n+1) (chia hết cho 6, vì chia hết cho 2, 3)