a=2008,b=2007.c=2006,则多项式a^2+b^2+c^2-ab-ac-bc
问题描述:
a=2008,b=2007.c=2006,则多项式a^2+b^2+c^2-ab-ac-bc
thanks!
答
a^2+b^2+c^2-ab-ac-bc
=1/2[(a-b)^2+(b-c)^2+(a-c)^2]
=1/2(1+1+4)
=3