[(3x+4y)^2 - 3x(3x+4y)] / (- 6y)其中X=1,Y= -3 化简 、求值

x²/xy-x/y 3x/4x+y - x-2y/4x+y (1-y/y+x)÷x/y²-x² （y-x)+x(x-y)^3-(y-x)^4 因式分解 (x-y) (x-2y)+(x+2y) (x-3y)-2(x-3y) (x-4y)= (x+3y-4)(2x-y) 计算（2x-3y)(x+4y)-(3x+y)(x-2y)（2x-3y)(x+4y)-(3x+y)(x-2y) 因式分解(x-2y)(x-3y)+(x-4y)(x-5y)+（x-3y)(x-5y)+(x-2y)(x-4y) 化简：2x-{-3y+[4x-(3x-y]} 4x*3-4x*2y-(x-y)因式分解 x^3+2x^2y-4x-8y 2x-{-3y+[4x-(2y-x)]} 1/(x-y)+1/(x+y)+2x/(x^2+y^2)+4x^3/(x^4+y^4)化简 (2x+y)(2x-3y)+x(2y+y) 2a(x-y)-4b(x-y) 计算 3x+4y/x-y+3y/y-x-4x/x-y 3x+4y/x-y +3y/y-x -4x/x-y x(4y-x)(x-3y)+y(3y-x)(x-4y)因式分解 (3x-y)(y+3x)-2(4x-3y)(4x+3y) (x-3y)(y+2x)-(4y-3x)(3x+4y)计算 5/4(x+y)(-x-y)^3*[-4/3(x-y)]*[-3/5(y-x)^2]