化简（y-1x）÷（x-1y）的结果是（）A.-yxB.-xyC.xyD.yx

Question

化简（y-(1)/(x)）÷（x-(1)/(y)）的结果是（　　）
A. -(y)/(x)
B. -(x)/(y)
C. (x)/(y)
D. (y)/(x)

Answer 1

(y−(1)/(x))÷(x−(1)/(y))=((xy)/(x)−(1)/(x))÷((xy)/(y)−(1)/(y))=(xy−1)/(x)÷(xy−1)/(y)=(xy−1)/(x)×(y)/(xy−1)=(y)/(x)．故选D．