1/2xy-1/3xy=-1/6xy这个是错的吧,急!

1/2xy-1/3xy=-1/6xy这个是错的吧,急! (6-2xy)(2-6xy)=4(3-xy)(1-3xy)如题,(6-2xy)(2-6xy)怎样化到4(3-xy)(1-3xy)? [6xy-3(xy-1/2x的平方y]/3xy=? 1/2xy(2/3xy²-2xy) 2xy(5xy的2次方+3xy-1) 2xy(5xy的2次方+3xy-1) （1）3xy-4xy-(-2xy) 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 当x=3,y=3分之1时,求代数出3xy-[2xy-2(xy-2分之3xy)+xy]+3xy的值 已知（x+1）*（x+1）=-Iy-1I,求2（xy-（5xy）*（5xy））-3（（xy）*（xy）-xy） [(xy-2)2次方-(-xy-1)(xy-4)]除(-3分之1xy) 计算 -6xy(-1/3xy+2/3y-1) ( )-(x^2+3xy)=-xy-1/3y^2 (2xy的2次方)×(3分之1xy)= 已知(x+1)²+|y-1|=0,求2(xy-5xy²)-(3xy²-xy)得值 x2—2xy=3y2 2xy+y2=1 怎么解这个方程组? 3xy乘以[6 xy-3(xy-1/2x的平方y)] 1-2/x+y=xy,4y+6x=xy.求xy的解?