已知2x=-y,求分式x^2-y^2分之xy的值_数学解答

已知2x=-y,求分式x^2-y^2分之xy的值

人气：291 ℃　时间：2019-10-17 03:30:09

解答

2x=-y
y=-2x
xy/(x^2-y^2)
=x*(-2x)/[x^2-(-2x)^2]
=-2x^2/[x^2+4x^2]
=-2x^2/5x^2
=-2/5