计算 -1/2(2x+3y)-2/3(4x-5y).

计算:(x+3y)(2x-y) 计算:(2x-3y)(x+y) 计算:(-x-2y) * (3x-y) 计算：(x+y)-3(x-2y). 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) (x-3y)(y+2x)-(4y-3x)(3x+4y)计算 计算(x+y)(x+y)^2(-x-y)^3 3x(x-y)+2y(x-y) 计算 计算:(x-y)^2*(x+y)^3*(-x-y)^3*(y-x)^4 计算(3x+y-2)(4x-y+2) 计算（4x^2y-9y)/(2x+3) 计算：3x-2y- [-4x+(z+3y)] 计算x^2y^-3（x^-1y）^3 (2x+y)(x+3y-1)计算 计算（2x-3y)(x+4y)-(3x+y)(x-2y)（2x-3y)(x+4y)-(3x+y)(x-2y) 计算2/3x-2/x+y(x+y/3x-x-y)/x-y/x 计算:[(2x - 3y)^2 - (x-y)(4x+2y)] / 2y 计算：x+2y/x-y+2x/y-x-3y/x-y