A=1996X+1995,B=1996X+1,C=1996X+1997.求A"+B"+C"-AB-BC-CA的值

问题描述:

A=1996X+1995,B=1996X+1,C=1996X+1997.求A"+B"+C"-AB-BC-CA的值

A²+B²+C²-AB-BC-AC
=1/2(A-B)²+1/2(A-C)²+1/2(B-C)²
=1/2((1994²+2²+1996²)
=3980028