计算:1÷(x^-2 + y^-2)
计算:(x+y/x-y)÷(xy+x^2)
计算:(x-y)^7÷(y-x)^6+(-x-y)^3÷(x+y)^2
[(2x+y)(x-3y)+y(x+3y)]÷(2x)计算,
计算:1/2x-1/x+y×(x+y/2x-x-y)
计算:1/(2x) - 1/(x+y)((x+y)/(2x) - x - y)
(2x+y)(x+3y-1)计算
计算:(-x-2y) * (3x-y)
计算:(2x+y-1)²
计算:1.(x-1)^2+2(1-x) 2.(x-y)/(x+3y)÷(x^2-y^2)/(x^2+6xy+9y^2)-
计算(1)x/x+y-x/x-y (2)a+2+4/a+2 (3)x^2-y^2/xy÷(x+y)
计算3x[xy-2x(1/y-x/3]+3y(x²-y²)
计算:(x-y)^2*(y-x)^2*(x-y)^6