※ 引述《knuk (金锋)》之铭言： : a,b,c相异，满足下式 : a^3+b^3+2(a^2+b^2)=b^3+c^3+2(b^2+c^2)=a^3+c^3+2(a^2+c^2) : 求a+b+c : 麻烦大家帮忙了，感谢 (a - c)(a^2 + ac + c^2) = 2(c + a)(c - a) => (a - c)[a^2 + ac + c^2 + 2a + 2c] = 0 => (a + 1)^2 + (c + 1)^2 + ac = 2 同理(b + 1)^2 + (c + 1)^2 + bc = 2 => (a + b + c + 2)(a - b) = 0 => a + b + c = -2 --

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