xy=4 x-y=-7.5 则3（xy-2/3y)-1/2(2x=4xy)-(-2x-y)

已知x+y=4,xy=3,则-xy-xy= 若x-y=4,xy=1,则(2x+y-2xy)-(3x+2y+xy)-(4xy+3y-5x)= （-3x^y+2xy)-( )=4x^+xy 当x-y=2xy时,求4x-3xy-4y/xy xy=4 x-y=-7.5 则3（xy-2/3y)-1/2(2x=4xy)-(-2x-y) 已知x+y=3,xy=1,则4x+3xy+4y= 已知xy=-3,x+y=-4,则x²+3xy+y²=? 已知x/y=3/4 ,则3xy-2y/2x+4xy=? |x|/x+y/|y|+xy/|xy|= x*x+xy=3,xy+y*y=2,则x*x+2xy+y*y=________? 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+xy+3+4xy-7化简,已知x=5,y=6 若x+y分之xy=2,则-x+3xy-y分之3x-xy+3y=多少? 若xy/x+y=2,则3x-5xy+3y/-x+3xy-y=?/是分之 若x+y分之xy=2,则-x+3xy-y分之3x-xy+3y=多少? 已知x+xy+y=3,则(3x+2xy+3y)/(2x+xy+2y)= 已知xy/x+y=1/2,则代数式3x-5xy+3y/-x+3xy-y= 若xy/x+y=2,则3x-xy+3y/-x+3xy-y=