设a,b,c均为大于1的整数,且a>b>c,若(ab-1)(bc-1)(ca-1)能被abc整
问题描述:
设a,b,c均为大于1的整数,且a>b>c,若(ab-1)(bc-1)(ca-1)能被abc整
设a,b,c均为大于1的整数,且a>b>c,若(ab-1)(bc-1)(ca-1)能被abc整除,求a,c
答
答案是5.3.2把(ab-1)(bc-1)(ca-1)展开后,除以abc得到abc-a-b-c+1/a+1/b+1/c-1/abc ,因为结果为整数,又有abc-a-b-c是整数,得 1/a+1/b+1/c-1/abc是个整数,因a>b>c>1,知 1/a+1/b+1/c-1/abc=1假定c=2,b=3,带入,得a...