Question

y=

x

x-1

的导数为（　　）

A．- 1 (x-1)2

B． 1 (x-1)2

C．- 2x-1 (x-1)2

D． 2x-1 (x-1)2

Answer 1

y′=

x′(x-1)-x(x-1)′

(x-1)2

=

(x-1)-x

(x-1)2

=

-1

(x-1)2

，
故选A．