a²+b²+c²=ab+bc+ca 求(3a+2b+c)²º¹²

问题描述:

a²+b²+c²=ab+bc+ca 求(3a+2b+c)²º¹²

解a²+b²+c²=ab+bc+ca2a²+2b²+2c²-2ab-2bc-2ca=0(a²-2ab+b²)+(a²-2ac+c²)+(b²-2bc+c²)=0(a-b)²+(a-c)²+(b-c)²=0a-b=0 a-c=...