n,a應(yīng)該都是整數(shù)吧因?yàn)閚＞1,a＞1,所以a^n-1=(a-1)[a^(n-1)+a^(n-2)+...+1],所以a-1|a^n-1由于a^n-1是質(zhì)數(shù),故a-1=a^n-1或1若a-1=a^n-1,那么a=a^n,這與n＞1且a＞1矛盾!所以a-1=1即a=2下面用反證法證明n為質(zhì)數(shù)若n不為質(zhì)...