若x+y=1,则1/2x²+xy+1/2y²=

问题描述:

若x+y=1,则1/2x&sup2+xy+1/2y²=
rt.

1/2x²+xy+1/2y²=(1/2)(x²+2xy+y²)
=(1/2)(x+y)²
=(1/2)*1²
=1/2