(1)
当x≠0时,
f′(x)=
=x[g′(x)+e?x]?g(x)+e?x
x2
,xg′(x)?g(x)+(x+1)e?x
x2
当x=0时,由导数定义,有:
f′(0)=
lim x→0
=f(x)?f(0) x?0
lim x→0
=g(x)?e?x
x2
lim x→0
=g′(x)+e?x
2x
lim x→0
=g″(x)?e?x
2
,g″(0)?1 2
所以:
f′(x)=
.
,xg′(x)?g(x)+(x+1)e?x
x2 x≠0
,g″(0)?1 2 x=0
(2)
因为在x=0处,有:
f′(x)=lim x→0
lim x→0
xg′(x)?g(x)+(x+1)e?x
x2
=
lim x→0
g′(x)+xg″(x)?g′(x)+e?x?(x+1)e?x
2x
=
lim x→0
=g″(x)?e?x
2