要想x51最小,x51就要与其它的数相差的最小,也就是x50与x51差1,x49与x51差2、x48与x51差3、.x1与x51差50得x1到x51是公差d为1的等差数列,且n=51所以x1+x2+x3+.x50+x51=Sn=n*x1+n*(n-1)d/2=51x1+1275=1998得x1=723/51≈...