计算：((x^-1)-(y^-1))/((x^-2)(y^-2)) （结果不含负整数指数幂））计算：((x^-1)-(y^-1))/((x^-2)(y^-2)) （结果不含负整数指数幂）

计算：(1+ y/x-y )·(1- x/x+y) 计算(x+y-1)^2 计算x(y-1)+1-y 计算:2/x+1/(x-y) 计算：(y+1)/x*(x+1)/y-(y-1)/x*（x-1)/y的值是? 计算:(x-y)(1/9x-y)-(1/3x-y)(1/3x+y) (x+y)(x-y)-(2x+y)(x-y+1)计算要过程 [(x^-1)-(y^-1)]除以[(x^-1)+(y^-1)] 计算 计算：1/(x-y)+1/(2y-2x) 计算(2x+y+1)(2x+y-1) 计算：1(y-x)+1/(2y-2x) x^-2-y-2分之x^-1-y^-1计算 (y-1/x)÷（x-1/y）如何计算 计算(2x-y+1)(2x+y-1) (x y+1)(x y-1)计算过程? 计算：5x-2y-6+ (1/x) + (1/y) (x-3y-1)(x+3y-1) 计算. 计算(x-2y+1)(x+2y+1)