x+y=25 (1)2x-y=8 (2)

x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 已知X*X+Y*Y+6X-8Y+25=0 求（Y/X)+(X/Y)-2=? 【2(x-y)^3-8(x-y)^2(x+y)+6y(x-y)^2】/2(x-y)^2= （x-y)(x+y)-(x+y)^2+2y(y-x),其中x=1,y=3. 2y(x+二分之一y)-[(x+y)(x-y)+2y(y+x)],其中|x-1|=2 已知x求^2+y^2-6x-8y+25=0求1/x-y /x+y/x^4-y^4 [(2x-y)^2-y(y-4x)-8x]其中x=-1/2 9y=3x-(x-1),4(x+y)-(2x+4)=8y x+y=1 5x-2y=8 3x-y=7 2x-y=3x表示y和用y表示x 若x-y=1 化简（x+y)(x^2+y^2)(x^4+y^4)(x^8+y^8)(x^16+y^16) [(2x+y)²-y(y+4x)-8x】/4x,其中x=-1,y=2005 急 已知x+y=a,2x-y=-2a,求[（x/y-y/x)/(x+y)-x(1/x-1/y)]/[(x+1)/y]的值 若2/x-1/y=3,求[y/x-y/x-y(x-y/x-x+y)]/x-2y/x的值 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)的值 已知x^2+y^2-8x+12y+52=0 ,求1/2x-1/x-y(x-y/2x-x^2+y^2) 已知x^2+y^2-8x+12y+52=0 ,求1/2x-1/x-y(x-y/2x-x^2+y^2) 12y(x-y)^2-8(x-y)^3=? x+2y=2x+y+1=7x-y 求：2x-y?