若（x+y-3）^2+(x-y+5)^2=0,则x^2-y^2的值为 ?

若3x-5y=0,则x+y/x=（）,x-y/y=（）,2x-3y/2x+3y=( ) 若x-y分之x+y=3,求式子x+y分之5(x-y)—2（x-y）分之x+y的值 （x-y）^3×（y-x）^4+（x-y）^2×（y-x）^5 (5)若x/2=y/3(y不为0）则x/y=____,x+y/y=___,y/x-y=___. 2(x-y)+3（x+y）2-5(x-y)-8（x+y）2-（x-y） 化简:5(x-y)+2(x+y)-3(x-y) 2（x-y）²-3(x-y)(-y-x) [(x+y)(x-y)-(x-y)的平方+2y(x-y)]除以(4y)请帮我一下写两道计算题[(x+y)(x-y)-(x-y)的平方+2y(x-y)]除以(4y)[（3x+2y）（3x-2y）-（x+2y）（5x-2y）]除以（4x） 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) (2x-3y)-(5x-y) (2X-3y)-(5x-y) (2x-5y)(3x+y) 因式分解(x-2y)(x-3y)+(x-4y)(x-5y)+（x-3y)(x-5y)+(x-2y)(x-4y) (2x+y)²+(x+3y)(x-3y)-x(5x+8y)因式分解 先化简,再求值 [2/3x - 2/x+y（x+y/3x -x-y）]*x/x-y,其中5x+3y=0 [2(x-y)^5-8(x-y)^2(x+y)+6y(x-y)^2]÷2(x-y)^2[2(x-y)^3-8(x-y)^2(x+y)+6y(x-y)^2]÷2(x-y)^2 若x,y互为相反数（y≠0）,则2x+5+2y+3x/y=____ 若x-y/x+y=5,求x-y/2x+2y+5x+5y/3x-3y的值