若a=2009x+2007,b=2009x+2008,c=2009x+2009,则多项式a方+b方+c方-ab+bc+ca的值等于多少?

a-b=-1b-c=-1c-a=2原式=a²+b²+c²-ab-bc-ac=(1/2)(2a²+2b²+2c²-2ab-2bc-2ac)=(1/2)[(a²-2ab+b²)+(b²-2bc+c²)+(c²-2ac+a²)]=(1/2)[(a-b)²+(b-c)&su...