若2x=-y,则x²-y²分之xy等于

问题描述:

若2x=-y,则x²-y²分之xy等于

若2x=-y,
则x²-y²分之xy
=x*(-2x)/(x²-(-2x)²)
=-2x²/(x²-4x²)
=-2x²/(-3x²)
=2/3