a^2+b^2+c^2=ab+bc+ca 2a^2+2b^2+2c^2-2ab-2bc-2ca=0 a^2-2ab+b^2+a^2-2ca+c^2+b^2-2bc+c^2=0 (a-b)^2+(a-c)^2+(b-c)^2=0 a-b=0 a-c=0 b-c=0 所以a=b=c a+2b+3c=12 6a=12 a=2 所以a=b=c=2 a+b²+c³ =2+2^2+2^3 =2+4+8 =14