Question

函数y= 1nx x 2 +1 的导数是______．

Answer 1

因为y=

1nx

x 2 +1 ，

所以 y ′ =

(lnx ) ′ •( x 2 +1)-lnx•( x 2 +1 ) ′

( x 2 +1 ) 2

=

1

x ( x 2 +1)-2xlnx

( x 2 +1 ) 2

=

x 2 +1-2 x 2 lnx

x( x 2 +1 ) 2 ．