a=2006x+2006,b=2006x+2007,c=2006x+2008求a^2+b^2+c^2-2ab-2ac.急,

a=2006x+2006,b=2006x+2007,c=2006x+2008求a^2+b^2+c^2-2ab-2ac.急,
a=2006x+2006,b=2006x+2007,c=2006x+2008求a^2+b^2+c^2-2ab-2ac.急,

a=2006x+2006,b=2006x+2007,c=2006x+2008求a^2+b^2+c^2-2ab-2ac.急,
a-b=-1,b-c=-1,c-a=2
原式=a^2+b^2+c^2-ab-bc-ac
=(2a^2+2b^2+2c^2-2ab-2bc-2ac)/2
=[(a^2-2ab+b^2)+(b^2-2bc+c^2)+(c^2-2ac+a^2)]/2
=[(a-b)^2+(b-c)^2+(c-a)^2]/2
=(1+1+4)/2
=3

a^2+b^2+c^2-2ab-2ac=(a-b)^2+(a-c)^2-a^2=5+(2006x+2006)^2

=3

=a^2+b^2+c^2-ab-bc-ac
=(2a^2+2b^2+2c^2-2ab-2bc-2ac)/2
=[(a^2-2ab+b^2)+(b^2-2bc+c^2)+(c^2-2ac+a^2)]/2
=[(a-b)^2+(b-c)^2+(c-a)^2]/2
=(1+1+4)/2
=3