已知x+y=1,则1/2x2+xy+1/2y2=_.
问题描述:
已知x+y=1,则
x2+xy+1 2
y2=______. 1 2
答
∵x+y=1,
∴
x2+xy+1 2
y2,1 2
=
(x2+2xy+y2),1 2
=
(x+y)2,1 2
=
.1 2