x/y-2/5=0 ①500x+250y=22500000 ②

x*x+2x+y*y-4y+5=0 x= y= x/y-2/5=0 ①500x+250y=22500000 ② 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*y)的值 已知x*x+4x+y*y-2y+5=0,则x*x+y*y=? （x+y-5)*（x+y-5)+（x-y+3)=0 x*x-y*y 已知:3x-5y=0,求x/y,x-y/y,x-y/x x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) 先化简,再求值 [2/3x - 2/x+y（x+y/3x -x-y）]*x/x-y,其中5x+3y=0 先化简,再求值:[3x-2/x+y(x+y/3x-x-y)]/(x-y/x),其中5x+3y=0 x*x+y*y-2x+4y+5=0求x, 若3x-5y=0,则x+y/x=（）,x-y/y=（）,2x-3y/2x+3y=( ) .先化简再求值：（2x+y）（2x+y)-(2x-y)平方其中X,Y满足X平方+Y平方-2X+4Y+5=0 已知X.x+y.y-4x+2y+5=0,求4X.X-12X Y+9Y.y的值 解方程（y-x-5)y'-y+2=0 {x+y=1 ,xy=-6{x(2x-3)=0,y=x²-1{(3x+4y-3)(3x+4y+3)=0,3x+2y=5{(x-y+2)(x+y)=0,x²+y²=8{(x+y)((x+y-1)=0,(x-y)(x-y-1)=0 (5)若x/2=y/3(y不为0）则x/y=____,x+y/y=___,y/x-y=___. 已知x²+4y²-4x+4y+5=0,求：(x^4-y^4)/[(2x-y)(x+y)]*(2x-y)/(xy-y²)/[(x²+y²)²/y²]