内容正文:
书书书
P(X=4)=C13·
2
3 (· )13
2
= 2
9
,
P(X=5)=C23 (· )23
2
·
1
3
= 4
9
,
P(X=6) (= )23
3
= 8
27
,
!"
X
#$%&'
:
X 3 4 5 6
P
1
27
2
9
4
9
8
27
E(X)=3×1
27
+4×2
9
+5×4
9
+6×8
27
=5.
(2)
(')
n
*#+,-$'
n+1
$
,
./01
2
1
*,345678
,
!"
Pn =C
1
n·
2
3 (· )13
n-1
=2n
3n
,
9
Sn =P1+P2+… +Pn-1+Pn
= 2
3
+4
32
+6
33
+… +2(n-1)
3n-1
+2n
3n
,
.
1
3
Sn =
2
32
+4
33
+6
34
+… +2(n-1)
3n
+2n
3n+1
,
:;<=-
2
3
Sn =
2
3
+2
32
+2
33
+… +2
3n
-2n
3n+1
=2×
(13 1-13 )n
1-1
3
-2n
3n+1
=1-2n+3
3n+1
,
!"
P1+P2+… +Pn =Sn = (32 1-2n+33n+ )1 .
(3)
>?@AB#CD*#+,-$'
n-1
$#
EFGHAB
1
*
,
.)I*#+,-$JK'
n
$L
n+1
$
,
M
“
+,-
n
$
”
'NO
A,“
+,-
n+1
$
”
'N
O
B,A
P
B
QRSNO
,
('
P(A)=an,P(B)=
2
3
an-1,
!"
an+
2
3
an-1 =1,n≥2,
T
an-
3
5
=-2
3
(an-1-
3
5
),n≥2,
('
a1 =
1
3
, {.U& an- }35 QVW' -415,
XY'
-2
3#ZYU&
,
!"
an-
3
5
=-4(15 - )23
n-1
,
!"
an =
3
5
-4
15 (· - )23
n-1
= 3
5
+2
5 (· - )23
n
,
('
0< -2
3
<1,
.[
n→+∞ \ (, - )23
n
→0,!" an→
3
5
,
!"?]AB*U#^_`a
,anbcdeU
3
5
.
!"#$%&'()
(
*
)
+#,-./0"12
3
、
456
BDAAAB DAACAA
78
:
1.
('
f(x)=sinx+ex,
!"
f′(x)=cosx+ex,
!"
f′(0)=cos0+e0 =2.
2.
('
f′(x)= 2
2x-1
-1,f′(1)=1,
!"fg
y=f(x)
>h
(1,-1)
i#jgkl'
x-y-2=0.
3.
m
y=x2,
槡y= x
{
,
n-
x=0,
y={ 0L
x=1,
y=1{ ,
!"opq$#rs'∫
1
0(槡x-x
2
)d (x= 23x
3
2
-1
3
x)3
1
0
= 1
3
.
4.f(2)=2a-1,f′(x)=(ax-1+a)ex-2,
.
f′(2)=3a-1,
!"fg
f(x)
>h
(2,f(2))
i#j
gkl'
y-2a+1=(3a-1)(x-2),
tuh
(3,3)
J-
a=1,
.
f′(x)=xex-2,
v
f′(x)>0,
-
x>0,
!"wU
f(x)
#xyz`{|'
(0,+∞).
5.
v
lnx=t,
.}Z;
lnxf(lnx)>x
~��-
tf(t)>et,
��wU
g(x)=xf(x)
ex
,
.
g′(x)=xf′(x)-(x-1)f(x)
ex
>0,
wU
g(x)
xyz`
,
�
g(1)=1,
!"}Z;
tf(t)>et
tf(t)
et
>1=g(1),
T
g(t)>g(1),
!"
t>1,
!"
lnx>1,
n-
x>e,
!"}Z;#n�Q
(e,+∞).
6.
m��J-
f′(x)=x2+2mx+n,
('
f′(x)
'�wU
,
!"
m=0,
�
f(x)= 1
3
x3+nx+2,
f(1)= 1
3
+n+2=-2
3
,
n-
n=-3,
!"
f′(x)=x2-3.
�
g(x)=ex(x2-3),
.
g′(x)=ex(x2-3+2x)
=ex(x-1)(x+3),
��J�wU
g(x)
>{|
[0,1]
Gxyz=
,
>{|
(1,2]
Gxyz`
,
�wU
g(x)
>
{|
[0,2]
G#���'
g(1)=-2e.
��
(B).
7.f(x)
#���Q
(0,+∞),
f′(x)=x-2+a
x
=x
2-2x+a
x
,
CwU
f(x)
2:�}�#��h
,
.
x2-2x+a=0
>
(0,+∞)G22�}�#�
U�
,
9'
x1,x2,�0<x