X*Y=XY/X+Y,求2*(10+10)的值

已知x+y=-10,xy=16求x²+y²,(x-y)²,(x+2)(y+2),x²-xy+y².求值！ x-y=2,x方+y方=10,求xy,(x+y)^2,x+y 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| 已知:x>0,y>0,且x- 10√xy+25y=0,求2x+√xy+3y/x+√xy-y x的平方-2xy+y的平方-6y+10=0,求x,y 已知x平方+y平方-10x-6y+34=0求(x-y/x+y)平方/x平方-y平方/xy乘x平方+2xy+y平方/x平方-xy的值 已知2x+xy=10,3y+2xy=6.求4x+8xy+9y=? 已知x^2+9y^2-2x-6y+2=0,求{-（xy/（x-y）^2}^4*(y^2-xy/x)^3*x^4/y^10/(x/xy-y^2)^5的值 已知y-2x=10,求[2y(x-y)-(x-y)²+(x+y)²-2xy]÷4y的值 (x+y)^2/y^2-xy÷[-y^2+xy/(x-y)^2,x=0,y=根号10 已知2x-y=10,求式子[(x^2+y^2)-(x-y)^2+2y(x-y)]/4y (4xy-2y²)/4y是怎么变成=2y(2x-y)÷4y x^2+4y^2-6x+4y+10=0,求x^4-y^4/(x+2y)(x-2y)*x+2y/xy^2+y^3除以（x^2+y^2/y)^2的值 已知实数xy,满足10x²-2xy+y²+6x+1=0,求x+y 已知X+y=10,XY=24,求(X-Y)(X-Y)的值 已知x,y满足xy-x-y=10,求整数x,y的值 已知x²y²+x²+y²=10xy-16 求x,y 一道初二下学期的数学题x*x+y*y-2x-6y+10=0,求分式[(x+y)(x-y)]/xy的值