若2x=-y,则x²-y²分之xy等于?_数学解答

若2x=-y,则x²-y²分之xy等于?

人气：452 ℃　时间：2020-05-22 12:39:05

解答

2x=-y,y=-2x
x²-y²分之xy
xy/(x²-y²)=x*(-2x)/[x²-(-2x)^2]
=-2x²/(x²-4x²)
=-2x²/(-3x²)
=2/3