3x^2y-[7x-4(x^2y+2x-3)]计算（要过程）计算：a-4分之1(1-3分之1a）-3分之1（2-4分之1a）

x(x-y)2-(y-x)3 计算(x^8-x^7y+x^5y^3-x^4y^4+x^3y^5-x^y^7+y^8)(x^2+xy+y^2) 化简3(x-y)-7(x--y)+2(y-x) [2/3x-2/x+y(x+y/3x-x-y)]/x-y/x 化简：{2/3x-2/(x+y)[(x+y)/3x-x-y]}/(x+y)/x 计算2/3x-2/x+y(x+y/3x-x-y)/x-y/x 化简3x-2/(x+y)[(x+y)/3x-x-y]÷(x-y)/x (x-y) (x-2y)+(x+2y) (x-3y)-2(x-3y) (x-4y)= x²/xy-x/y 3x/4x+y - x-2y/4x+y (1-y/y+x)÷x/y²-x² (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) 计算:1/(x-y)-1/(x+y)-2y/(x^2+y^2)-4y^3/(x^4+y^4)-8x^7/(x^8+y^8) 因式分解x(x+y)(x-y)-x(x+y)^2 x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 化简y(x+y)+(x+y)(x-y)-x^2 若2x-3y+4=0则x（x*x-1)+x(5-x*x)-6y+7 (2x+y)(2x-3y)+x(2y+y) 2a(x-y)-4b(x-y)