25(x+y)^2-9(x-y)^2

1、x(x-y)(x+y)-x(x+y)^2 1) (2x+5y)(2x-5y)(-4x^2-25y^2) 2) [（x+y)(x-y)-(x-y)^2+2y(x-y 因式分解25(x +y)^-9(x-y)^2 已知4x=9y求(1)x+y/y (2)y-x/2x (1)(x^2/x)-y-x-y 【(x-y)^2+(x+y)(x-y)】除以 2x 化简：x-y/x+3y÷x^-y^2/x^2+6xy+9y^2-(xy/x+y) [(-x-y)(-x+y)-(x+y)^2-x(y-y^2)}÷1/2y 化简求值:x/[9(x-y)^2]*[(x^2-y^2)/(x+y)]+{[(x^2+2)/(x+y)]-2} x^2-y^2/x+y-4x(x-y)+y^2/2x-y, (x+y)^2(x-y)^2-(x-y)(x+y)(x^2+y^2)分解因式 化简:(x-3y)(x+y)-(x-2y)(x+2y)-(x-y)平方