 =  =   =  ( ) ( )LOG 1 LOGX U UA AX A U A U

3.4.Đạo hàm:  =  =   =  

( ) ( )

log 1 logx u u

a

a

x a u a u.ln .ln

n

n

1

(ln ) lnu n u=   = (ln ) 1, ( 0) (ln )u ux x ux u