m是奇数，且m>=3 =>m可以用表达式2n-1，n>=2 =>m²-1 = (2n-1)²-1 =>m²-1 = 4n²-4n+1-1 =>m²-1 = 4n²-4n =>m²-1 = 4n(n-1) =>m²-1 = 4*奇数*偶数 由于n>=2，则4*奇数*偶数必然能被8整除 =>m²-1必然能被8整除 =>m(m²-1)必然也能被8整除
