实数a,b,c满足a^2+b^2+c^x=667,则代数式(a-b)^2+(b-c)^2+(c-a)^2的最大值是

2025-01-04 00:41:44
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回答1:

(a-b)^2+(b-c)^2+(c-a)^2
=a^2+b^2+b^2+c^2+c^2+a^2-(2ab+2bc+2ac)
=2*667-(2ab+2bc+2ac)
又a^2+b^2>=2ab;
b^2+c^2>=2bc;
c^2+a^2>=2ac;
所以2ab+2bc+2ac<=a^2+b^2+b^2+c^2+c^2+a^2=2*667;
所以(a-b)^2+(b-c)^2+(c-a)^2
=2*667-(2ab+2bc+2ac)
<=2*667-2*667=0
所以最大值为0.