Question

a=1999x+2000 b=1999x+2001 c=1999x+2002 a方+b方+c方-ab-ac-bc=?

Answer 1

-a=1

c-b=1

c-a=2

a²+b²+c²-ab-ac-bc

=(1/2)(a²-2ab+b²+b²-2bc+c²+c²-2bc+a²)

=(1/2)[(b-a)²+(c-b)²+(c-a)²]

=(1/2)(1²+1²+2²)

=6/2

=3