4(x-2y)2-9(3x-4y)2

(x+3y-4)(2x-y) x/x-y*y^2/x+y-x^3y2/x^4-y^4/x^2/x^2+y^2 (2x+y)(2x-3y)+x(2y+y) 2a(x-y)-4b(x-y) 9y=3x-(x-1),4(x+y)-(2x+4)=8y x^2-y^2/x+y-4x(x-y)+y^2/2x-y, (2x-y)(2x+y)-2(3x-4y)(4y+3x) 计算【3(x-y)^2(x+y)^-2/4(x+y)^2(x-y)^-2】^-2 （x+2)(x+3) (x-4)(x+1) (y+4)(y-2) (y-5)(y-3) 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 (x-3y)(y+2x)-(4y-3x)(3x+4y)计算 计算（2x-3y)(x+4y)-(3x+y)(x-2y)