-2^3y[3xy^2-3xy＋1】=【】【过程】

(-3xy+2xy)-(4xy+xy) 2xy-xy-(-3xy)= ( )-(x^2+3xy)=-xy-1/3y^2 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 xy－3xy＋2xy－xy 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 [6xy-3(xy-1/2x的平方y]/3xy=? 计算（-3分之1xy²）²×[xy（2x-y）+xy²]= 2x²y-3(2xy-xy)-xy 已知(x+1)²+|y-1|=0,求2(xy-5xy²)-(3xy²-xy)得值 3xy²-[xy-2(xy-3/2x²y)+3xy²]+3xy²,其中x=3,y=-1/3 化简求值 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 （x＋2y-3xy）-（-2x-y+xy）,其中x+y=,xy=-,求值. 已知xy/x+y=1/2,则代数式3x-5xy+3y/-x+3xy-y= （x+2y-3xy)-(-2x-y+xy),其中x+y=1/2,xy=-1/2 已知3/(x-y)=1/xy 求(-x-2xy+y)/ (2x+3xy-2y) 4xy-[(x²+5xy-y²)-(3xy-1/2y)]x=3,y=-6 (-xy^-1)^2*(-xy^-2)^-3/(-x^2y^3)