x^2+y^2=25,x-y=1,求xy的值

x-2y=15,xy=-25,求x*x+4y*y-1 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 已知x+y=-1,xy=-2,求代数式-5（x+y)+(x-y)+x(xy+y)的值 1-2/x+y=xy,4y+6x=xy.求xy的解? 已知3/(x-y)=1/xy 求(-x-2xy+y)/ (2x+3xy-2y) 已知xy-x-y=11,求(xy-1)^2+(x+y-2)(x+y-2xy)的值. x+y=1,xy=-2求(x²+y²+xy)/(x²+y²-xy) 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)+2(xy+y)的值 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 xy^2-e^x+e^y=1 求y' f(x+y,x-y)=(x^2-y^2)/2xy,求f(x,y)! 正数x,y满足x-y=2xy,求x-y/x+y的值. f(x+y,x-y)=2xy(x-y),求f(x,y) x^2+xy+x=36,y^2+xy+y=20,求x+y. 若x^2+xy+y=14,y^2+xy+x=28,求x+y