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