(k+1)/3=(3k+1)/2-1
乘以6得 2(k+1)=3(3k+1)-6
2k+2=9k+3-6
2k-9k=3-6-2
-7k=-5
k=5/7
当k=5/7时,代数式(k+1)/3的值比(3k+1)/2的值小1