已知x+y=1,则2/1X.X+XY+2/1y.y的值是多少?

问题描述:

已知x+y=1,则2/1X.X+XY+2/1y.y的值是多少?

2/1X.X+XY+2/1y.y
=2/1(X.X+2XY+y.y)
=2/1(x+y)^2
=2/1