若|x-1|+|y-2|=0,求1/xy+1/(x+1)(y+1)+1/(x+2)(y+2)+.+1/(x+2009)(
x+y=1,xy=-1/2,求x(x+y)(x-y)-x(x+y)2
已知x+y=-1,xy=-2,求代数式-5(x+y)+(x-y)+x(xy+y)的值
已知实数x,y满足x²+y²-xy+2x-y+1=0 求x y
若x,y满足x^+2y^-2xy+1=0,求xy的值
若x-y=4,xy=1,求(-2xy+2x+3y)-(3xy+2y-2x)-(x+4y+xy)的值
1/x-1/y=3,求2x+3xy-2y/x-y
(1)x(x-1)-(x^2-y)=-2,求{(x^2)+(y^2)}/2-xy
已知x+y=-1,xy=-2,求代数式-5(x+y)+(x-y)+2(xy+y)的值
(x+y-2xy)(x+y-2)+(1-xy)²
已知X+Y=-1,xy=-2,求代数式-5(x+y)+(x-y)+(xy+y)的值
x(x-1)-(x平方-y)=-3,求x平方+y平方-2xy
1、(-7x^y)(2x^y-3xy^3+xy) 2、((x-y)^6)/((y-x)^3)/(x-y)