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有一道高中数学题填空题:已知a,b,c是△ABC的三条边,比较大小:(a+b+c)~2__4(ab+bc+ca).这道题的解答可以用特殊值法.取a=b=c=1,得(a+b+c)~2=9,4(ab+bc+ca)=12,所以(a+b+c)~2<4(ab+bc+ca).将这道题稍微变形,就是全日制普通高级中学教科书(实验修订本·必修)数学第二册(上)第31页B组题的第6题:设a,b,c为
There is a high school math problem fill in the blank: Known a, b, c is △ ABC three sides, the size: (a + b + c) ~ 2__4 (ab + bc + ca). The answer to this question can be special (A + b + c) ~ 2 = 9, 4 (ab + bc + ca) = 12, so that a = b = c = + bc + ca). To slightly distort this question is the sixth question of the Bth set of the second full-text ordinary high school textbook (Experimental Revised Edition, math) (at) page 31: Let a, b, c is