x^2-10xy=-100,y^2-3xy=-40,求x^2-7xy-y^2及x^2-16xy+2y^2的值

（-3x^y+2xy)-( )=4x^+xy x*x+xy=3,xy+y*y=2,则x*x+2xy+y*y=________? 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 f(xy,x-y)=x^2+3xy+y^2,则f(x,y)=? 已知:x>0,y>0,且x- 10√xy+25y=0,求2x+√xy+3y/x+√xy-y 由已知x+y=-2,xy=3那么2(x+xy)-[(xy-3y)-x]-(-xy)等于多少? 当x-y=2xy时,求4x-3xy-4y/xy 已知x+y=-2,求代数式(6xy+10y)+[4x-2(3xy+2y-x)] 已知x+y=3,xy=-10,求（1）x平方-xy+y平方；（2）|x-y| 先化简,再求值：[-xy/(x-y)^2]^4*(x^2-xy/x)3*x^4/y^10÷(x/xy-y^2)^5先化简,再求值：[-(xy)/(x-y)^2]^4*(x^2-xy/x)3*x^4/y^10÷(x/xy-y^2)^5,其中x=-2,y=4. (x^3-2x^2+xy^2)/(x-y)+(x+y)(y-x)=? 已知2x+xy=10,3y+2xy=6.求4x+8xy+9y=? 已知X+Y=3XY,求2X+2Y-XY除以X+Y+2XY的值,要算理.已知X+Y=3XY,求2X+2Y-XY除以X+Y+2XY的值,要算理. (-x+2y)(2x+y)-(2x+y)(y-2x)-3xy=?因式分解 x+y=-3 xy+x+y=-2 x/y+y/x=? x-y/xy=( )/x^3y^2 已知x-xy=10,xy-y=2,则x-y=（ ）,-2xy+x+y=（ ）. 已知x+xy+y=3,则(3x+2xy+3y)/(2x+xy+2y)=