Question

y=

x2

x+3

的导数是（　　）

A． x2+6x (x+3)2

B． x2+6x x+3

C． x2 (x+3)2

D． x2-6x (x+3)2

Answer 1

y′=

(x2)′(x+3)-x2(x+3)′

(x+3)2

=

2x(x+3)-x2

(x+3)2

=

x2+6x

(x+3)2

故选A