a-b=3,b-c=-2∴a-b+b-c=a-c=1a²+b²+c-ab-bc-ca=½[(a²-2ab+b²)+(a²-2ac+c²)+(b²-2bc+c²)]=½[(a-b)²+(a-c)²+(b-c)²]=½×﹙3²＋2²＋...