已知a=2003x+2002,b=2003x+2003,c=2003x+2004,试求a*2+b*2+c*2-ab-ac-bc
问题描述:
已知a=2003x+2002,b=2003x+2003,c=2003x+2004,试求a*2+b*2+c*2-ab-ac-bc
答
显然 a - b = -1,b - c = -1,c - a = 2
a*2+b*2+c*2-ab-ac-bc
= a(a-b) + b(b-c) + c(c-a)
= -a - b + 2c
= (c-a) + (c-b)
= 2 + 1 = 3