化简(2x-3y)(2x+3y)(9y^2+4x^2)-(4x^2-9y^2)^2

(x+3y-4)(2x-y) 化简:(x-3y)(x+y)-(x-2y)(x+2y)-(x-y)平方 x/x-y*y^2/x+y-x^3y2/x^4-y^4/x^2/x^2+y^2 化简：x-y/x+3y÷x^-y^2/x^2+6xy+9y^2-(xy/x+y) (2x+y)(2x-3y)+x(2y+y) 2a(x-y)-4b(x-y) 化简：（2x-y)²-4(x-y)(x+y) 9y=3x-(x-1),4(x+y)-(2x+4)=8y 化简[(3x+4y)^2-(2x+y)(2x-y)+(-x+y)(5x-y)]除以-2y,其中x=-1,y=1 计算【3(x-y)^2(x+y)^-2/4(x+y)^2(x-y)^-2】^-2 (2x-y)(2x+y)-2(3x-4y)(4y+3x) 1.（（y+2x)(-2x+y)+4(x+2y)^2)/3y 2.（2(x-y)^3-8(x-y）^2(x+y)+6y( 已知4x=9y求(1)x+y/y (2)y-x/2x