若x=2,求（3x^3y+3xy^3-6x^2y^2)/(x^2y^3-x^3y^2)的值

若1/x-1/y=2,求3x-2xy-3y/x-xy-y的值3x-2xy-3y/x-xy-y 不好意思，是3x-2xy-3y/x-2xy-y 已知:x/y=-2,求x^2-2xy-3y^2/x^-6xy 若xy=2（x+y),求 （3x-5xy+3y)÷(-x+3xy-y) 的值 已知xy/x+y=6,求3x-2xy+3y/-x+3xy-y的值. 已知(xy)/(x+y)=6求(3x-2xy+3y)/(-x+3xy-y)的值. 若(y-x)/xy=3,求分式(2x+3xy-2y)/(x-2xy-y)的值 若y-x/xy=3,求分式2x+3xy-2y/x-2xy-y 若x+y=4 x-y=6 求xy(x^2+y)-y^2(xy+2x)-3xy的值求值 若x+y-5xy=0,求(2x-3xy+2y)/(x+2xy+y)的值 诺x+y=6,xy=4 求(5x-4y-3xy)-(8x-y+2xy) 若x+y=4,x-y=6,求xy(y^2+y)-y^2(xy+2x)-3xy的值. 若x-y=4,xy=1,求(-2xy+2x+3y)-(3xy+2y-2x)-(x+4y+xy)的值 x^+2xy+y^+4=16 x^-2xy+y^=16 求(3xy+6y^)+|x^-(2xy+2y^-3x^)|的值 已知x/y=2,求 [x^2-xy+3xy^2 ] / [ x^2+xy+6y^2]的值 已知xy=-2,x-y=3,求（x+y)（x-y)-y^2+（x-y)^2-（6x^2y-2xy^2)÷2y 当x-y=2xy时,求4x-3xy-4y/xy X-Y方=6 XY=2 求 3x²y-xy的立方 已知1/x-1/y=2,求3x+7xy-3y/2x-3xy-2y答案是1/x-1/y=2(y-x)/xy=2 得：x-y=-2xy(3x+7xy-3y)/(2x-3xy-2y)=[3(x-y)+7xy]/[2(x-y)-3xy]=(-6xy+7xy)/(-4xy-3xy)=xy/(-7xy)=-1/7 谁能帮我解释一下=[3(x-y)+7xy]/[2(x-y)-3xy]=(-6xy+7xy)/(-4xy-3xy) 是怎