x^2+y^2+2x 8x+17=0,x^2009+xy

已知x*x-4xy+4y*y=0 求[2x(x+y)-y(x+y)]/(4x*x-4xy+y*y)的值? （xy-x^2)乘以(xy)/(x-y) 方程组,x平方-xy+2x=0,x平方-2xy+y+8=0, 因式分解:8(x-2y)-x(7x+y)+xy. 2x+8y-xy=0(x>0,y>0),求x+y的最小值 （x^2+xy/x-y)/（xy/x-y)计算 x²+y²+2x-8y+17=0,求x的2009次方+xy 若(x*x+y*y)(x*x+y*y)-4x*x*y*y=0,求代数式(x*x+5xy+y*y)/(x*x+2xy+y* 已知3x*+xy-2y*=0,求(x/y)-(y/x)-(x*+y*)/(xy)的值.*是平方 {x,xy,lg(xy)}={0,|x|,y} 则log8（X^2+Y^2） 已知3x^2+xy-2y^2=0,求{(x+y)/(x-y)+4xy/(y^2-x^2)}/{(x+3y)*(x-y)} 已知x.x+y.y+8x+6y+25=0,求代数式(x.x-4y.y)/(x.x+4xy+4y.y)-x/(x+2y)的