已知x=—2/1y=-1求【(x.x+y.y)-(x-y)2+2y(x-y)】/(2y)的值
问题描述:
已知x=—2/1y=-1求【(x.x+y.y)-(x-y)2+2y(x-y)】/(2y)的值
答
【(x.x+y.y)-(x-y)2+2y(x-y)】/(2y)
=[x^2+y^2-(x^2-2xy+y^2)+2xy-2y^2]/(2y)
=[2xy+2xy-2y^2]/(2y)
=2x-y
=2*(-1/2)-(-1)
=-1