3x^2-2xy-( )=4x^2-xy-3y^2

（-3x^y+2xy)-( )=4x^+xy 3xy(x^2-xy^2+xy)-xy^2(2x^2-xy+2x) 化简:xy分之3x^2+2xy-xy分之2x^2-xy= 当x-y=2xy时,求4x-3xy-4y/xy xy-2{xy-[3x^2y-(4xy^2+0.5xy)]+4x^2y}+6xy^2 （X-3xy+4xy-y）-[-2x-2（xy-3/2xy）-y]+6xy的过程 -3(2x^2-xy)+4(x^2+xy-6) 因式分解x^3+2xy-x-xy^2= 4(x²+xy-6)-3(2x²-xy) -3(2x²-xy)+4(x²+xy-6) 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 (-3xy+2xy)-(4xy+xy) 因式分解X^3-2xy+xy^2 化简：3x^2-[5xy-(x^y-3xy)+4x^2y-8xy] 2x²y-3(2xy-xy)-xy 5xy²-{2x²y-[3xy²-(4xy²-2xy²)]}= 由已知x+y=-2,xy=3那么2(x+xy)-[(xy-3y)-x]-(-xy)等于多少? 已知x y=1,xy=-3,求2xy-4x 4(y-2(xy-x))