化简求值y/x-y +y立方/x立方-2x平方y+xy平方除以xy+y平方/y平方-x平方,其中x=2/3,y=-3

来源:学生作业帮助网 编辑:作业帮 时间:2024/05/07 13:53:17

化简求值y/x-y +y立方/x立方-2x平方y+xy平方除以xy+y平方/y平方-x平方,其中x=2/3,y=-3


原式=[y/(x-y)]+[y³/(x³-2x²y+xy²)]÷[(xy+y²)/(y²-x²)]

=[y/(x-y)]+{y³/[x(x²-2xy+y²)]}÷{y(x+y)/[-(x-y)(x+y)]}
=[y/(x-y)]+{y³/[x(x-y)²]}×[-(x-y)/y]

=[y/(x-y)]+{-y²/[x(x-y)]}

=xy/[x(x-y)]-y²/[x(x-y)]

=(xy-y²)/[x(x-y)]

=y(x-y)/[x(x-y)]

=y/x

=-3/(2/3)

=-9/2