Question

计算：(y+1)/x*(x+1)/y-(y-1)/x*（x-1)/y的值是?

Answer 1

(y+1)/x*(x+1)/y-(y-1)/x*（x-1)/y

=(y+1)(x+1)/xy-(y-1)(x-1)/xy

=[(y+1)(x+1)-(y-1)(x-1)]/xy

=(xy+x+y+1-xy+x+y-1)/xy

=(2x+2y)/xy