化简求值y/(x-y)+y³/(x³-2x²y+xy²)÷(xy+y²)/(y²-x²)

　　y/(x-y)+y³/(x³-2x²y+xy²)÷(xy+y²)/(y²-x²)
　　=y/(x-y)+y³/x（x-y)(x-y)÷[y(x+y)/(y-x)(y+x)]
　　=y/(x-y)-y³/x（x-y)²÷[y/(x-y)]
　　=y/(x-y)-y²/x（x-y)
　　=y(x-y)/x（x-y)
　　=y/x
　　= - 9/2
　　很高兴为你答疑,