a-b=√5+√3,b-c=√5-√3两式相加得：a-c=2√5a²+b²+c²-ab-ac-bc=(1/2)(2a²+2b²+2c²-2ab-2ac-2bc）=(1/2)[(a-b)²+(b-c)²+(a-c)²]=(1/2)*[(√5+√3)²+(√5-√3)&#...