《数学通报》2 0 0 1年 2月号数学问题1 3 0 0 :设 a,b,c,d∈R,且 a+ b+ c+ d=2 ,ab+ac+ ad+ bc+ bd+ cd=- 83 ,求 b+ c+ d的最大值和最小值 .除了《数学通报》上已给出的一种解法之外 ,本文再给出这一问题的两种解法 .为此 ,我们先计算 a2 + b2 + c2 + d2 =(a+ b+ c+ d) 2- 2 Mathematical Bulletin February 2010 Issues of Mathematics 1 3 0 0: Let a, b, c, d∈R, and a+ b+ c+ d=2, ab+ac+ ad+ bc+ bd+ cd=- 83, find The maximum and minimum values ​​of b+c+d. In addition to the one given in the “Medical Bullets”, this paper gives two solutions to this problem. To do this, we first calculate a2 + b2 + c2 + D2 = (a+ b+ c+ d) 2- 2