5.已知x = 0.67,y=0.33,求x^2 +y^2 +2xy-x-y的值

问题描述:

5.已知x = 0.67,y=0.33,求x^2 +y^2 +2xy-x-y的值

x^2 +y^2 +2xy-x-y
=(x+y)^2-(x+y)
= (x+y)(x+y-1)
=0