X+y=4,Xy=-12 求(1)XxX+yxy (2)XxXxy+Xxyxy

X+y=4,Xy=-12 求(1)XxX+yxy (2)XxXxy+Xxyxy XxX+yxy=3,Xy=1,X-y=? X*Y*XY=XXX求 X Y是多少?是一位数· x=-2|1 y=2|3 求代数式2x[xxx+xy+yyy]=?|为除 1-2/x+y=xy,4y+6x=xy.求xy的解? 已知X+Y=3,XY=-1,求2(X-Y)^4-9(X-Y)^2+12XY 已知x和y满足2x+3y=5,则当x=4时,代数式3(xXx)+12xy+（yXy)的值是（ ） x+y=4,xy=－12,求x^+y^,x^-xy+y^实际求：x平方＋y平方和x平方－xy＋y平方 若x-y=4,xy=1,求(-2xy+2x+3y)-(3xy+2y-2x)-(x+4y+xy)的值 x-y=1,xy=2.求：(-2xy+2x+3y)-(3xy+2y-2x)-(x+4y+xy)的值 .已知:x-y=1,xy=-2.求:(-2xy+2 x+3y)-(3xy+2y-2x)-(x+4y+xy)的值 已知x y=1,xy=-3,求2xy-4x 4(y-2(xy-x)) 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 设xy>0,且xy=4x+y+12,求xy的最小值 1/x-1/y=x,求5y+xy-5y/y-xy-x=? 已知x-y=3,xy=1,求（-2x+2x+3y)-(3xy+2y-2x)-(x+4y+xy) 已知x+y=3,xy=1,求代数式5xy+4x+7y+6x-3xy-4xy+3y的值. 当x-y=2xy时,求4x-3xy-4y/xy