问题 选择题
(
ex
x
)′
=(  )
A.-
ex
x
B.
xex-ex
x2
C.
xex+ex
x2
D.
xex-ex
x
答案

(

ex
x
)′=
(ex)x-ex(x)
x2
=
xex-ex
x2

故选B.

判断题
判断题