Μια άσκηση την ημέρα -...
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http://lisari.blogspot.gr
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:
lisari.blogspot.gr
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http://lisari.blogspot.gr
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2016
27
(1/4/2016) 10/4/2016
G : 0, R :
x
G(x) G(x) 3x , x (0, )2
G(1) 0
G'(1) 1
.
3x lnx ,x 0
G(x)0 ,x 0
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B. i. N G
ii. 3
3G(x) xG'(x) x ,x 0
. 31 3lnx x lnx ln lnx .
. B
G .
G : R R 2
:
x
G(x) G(x) 3x , x (0, )2
G(1) 0 G'(1) 1
. G R .
B. i. () ,
G
ii . () ()
xx 3
Cf 2 .
. B G ,
() yy .
.
31 3lnx x lnx ln lnx
.
.
1 1
3e G 3eGxc 3 c 2
1 1G(t)dt G(t)dt xe x 1 0 ,c 0
0,1
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1 ( )
. x > 0
2
2
4
x x G''( x ) 2xG'( x ) 3G'( x ) G''( x ) 3x 2G'( x ) xG''( x ) 3x
2 x x
2 2
G'( x ) G'( x )' 3lnx ' 3lnx c ,c R
x x, G'(1)
3ln1 c c 11
2 2 2 32
G'( x ) 13lnx 1 G'( x ) 3x lnx x G'( x ) 3x lnx x
x x
3 3G'( x ) x lnx ' G( x ) x lnx k , k R , G(1) k k 0 3G( x ) x lnx ,x 0 ,
3
x 0 x 0 x 0 DLH
3
lnxG(0 ) limG( x ) lim x lnx lim 0
1
x
.
3x lnx ,x 0G( x )
0 ,x 0
B. i.
2 23x lnx x ,x 0G'( x )
0 ,x 0
ii.
2 2 3 3 3
3
G'( x ) 3x lnx x xG'( x ) 3x lnx x xG'( x ) 3G( x ) x
3G( x ) xG'( x ) x ,x 0
G(0)=0 , 33G( x ) xG'( x ) x ,x 0
.
G 1, 2 2G'( x ) 3x lnx x 0 G G 1, 0 ,
x 0 lnx 0 x 1
lnx x 1 x 1
x
0
3
1
e
G
- +
G
1
3e
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3 3 3 3 3
3 3
1 3lnx x lnx ln lnx 1 lnx x lnx ln lnx ln lnx lnx x lnx 1
ln x lnx x lnx 1 lnG( x ) G( x ) 1 G( x ) 1
G G 1, 0 ,
1, .
.
3x lnx ,x 0G( x ) 0 0 x 0 x 1
0 ,x 0
xx CG 0 , 1 . G
3
1 1G 0
3ee
G x 0 ,x 0 ,1 1
0
E G( x )dx .
B.ii. 33G( x ) xG'( x ) x
1 1 1 1 1
13 3
00 0 0 0 0
3G( x ) dx xG'( x ) x dx 3 G( x ) dx xG( x ) G( x ) dx x dx
1 1 13 G(1) E 4E E ..
4 4 16
A.
x > 0
2
2
4
x x G''( x ) 2xG'( x ) 3G'( x ) G''( x ) 3x 2G'( x ) xG''( x ) 3x
2 x x
2 2
G'( x ) G'( x )' 3lnx ' 3lnx c ,c R
x x, G'(1)
3ln1 c c 11
2 2 2 32
G'( x ) 13lnx 1 G'( x ) 3x lnx x G'( x ) 3x lnx x
x x
3 3G'( x ) x lnx ' G( x ) x lnx k , k R , G(1) k k 0 3G( x ) x lnx ,x 0 , (1) G R , G( x ) G( x ) ,x R
x 0 x 0 , ( 1)
3 3G( x ) G( x ) ( x ) ln( x ) x ln( x )
G(0 ) 0 G R
3x ln x ,x 0G( x )
0 ,x 0
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32
x 0 x 0 x 0 x 0 x 0 DLH
2
G( x ) G(0 ) G( x ) x lnx lnxG'(0 ) lim lim lim lim x lnx lim 0
1x x x
x
2 23x ln x x ,x 0G'( x )
0 ,x 0,
B. i.
x , 0 . : y = CG
() G( x ) x ,x R . x=0
, (0,0) . R* .
2G( x )
G( x ) x ,x R* ,x R* x lnx , x R*x
( 2)
2(x) x ln x ,x R* '(x) 2x ln x x x 2ln x 1 (2) (x)= .
1 1
'(x) 0 x 2ln x 1 0 ln x x2 e
H
1 1 1
2ee e
1 1 1 0, 0, ,0
2ee e
2
x 0 x 0 x 0
2 3
1lnx xlim x lnx lim lim 01 2
x x
1 1 1 , , ,
2ee e
2
xlim x ln x
x
-
3
1
e
0
3
1
e
G
+ - - -
G
1
3e
1
3e
x
-
1
e
0
1
e
H
- + - +
H
1
2e
1
2e
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1
2e
(x)= G( x ) x ,x R
x=0
1
2e
(x)= 2 G( x ) x ,x R 3
( x=0)
1
0 2e
(x)= 4 G( x ) x ,x R 5
( x=0)
0 (x)= 2 G( x ) x ,x R 3
( x=0).
B. ii.
.i. CG 3 ()
xx (
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2 2 2
1 1 1 1 5E
16e 4e 16e8e e 4e e ..
.
G 1, 2 2G'( x ) 3x lnx x 0 G G 1, 0 , x 0 lnx 0 x 1
lnx x 1 x 1
3 3 3 3 3
3 3
1 3lnx x lnx ln lnx 1 lnx x lnx ln lnx ln lnx lnx x lnx 1
ln x lnx x lnx 1 lnG( x ) G( x ) 1 G( x ) 1
G G 1, 0 ,
1, .
.
1 13e G 3eG
c 3 c 2 x
1 1
F( x ) G(t )dt G(t)dt xe x 1 ,x 0 ,1
0,1
21 1
3eG 3eGc 3 c 2
1 1
F(0 ) F(1) G(t )dt G(t)dt 0
1 1 1 1
3eG 3eG 3eG 3eGc 3 c 2 c 3 c 2
1 1 1 1
G(t )dt G(t)dt G(t )dt G(t)dt
1
3eGc 3
13eG
c 2
G(t )dt 0 ,
1 1 3eG , 3eG
c 2 c 3
G(t )dt 0 3
1 1 1 10 1 1 3e G 0 , 1 3eG 0
c 3 c 2 c 2 c 3
G
G( t )dt 0
G(t )dt 0 G(t )dt G(t )dt 0 G(t )dt 0
-1
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1 12 3
c 2 c 3 ,
(3)
1
3eG3
13eG
2
G(t )dt 0
F(0 )F(1) 0 .Bolzano 0,1 F . .
2 ( )
A. :
2 2 3 2 2( ) 2 ( ) 3 ( ) ( )
2 ( ) ( ) 3 3ln 3lnG x G x G x G x
G x xG x x x x cx x x x x
x=1: c=1 :
2 2 3 32( )
3ln 1 ( ) 3 ln ( ) ln ( ) lnG x
x G x x x x G x x x G x x x cx
x=1: c=0 : 3( ) lnG x x x , 0x . (1)
G 0 :
3
3
0 0 0 0
3
ln(0) lim ( ) lim ln lim lim 0
1 3x x x x
x xG G x x x
x
.
( .. : ( ) ( )G x G x .
(1) x 0x : 3 3 3( ) ( ) ln( ) ( ) ln( ) ( ) ln( ), 0G x x x G x x x G x x x x )
. i) GC .
0, . 0x
1
2 2 2 3( ) 3 ln 3ln 1 0G x x x x x x x e
.
1
3( ) 0G x x e
G 1
3 ,e
G 1
30,e
.
GC ..
1
3e
1
31
3G e
e
0 0,
0, . 1
3e ..
1
3e..
1
3e
.
ii) E De L H. (0) 0G x=0.
0x 3 2 2 3 3( ) 3 ln 3 ln 3 ( )xG x x x x x x x x x G x . . 1x :
3 3 3 31 ln ln(ln ) ln 0 1 ln( ln ) ln 0 ln ( ) ( ) 1 0x x x x x x x x G x G x (1)
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( ) ln 1h x x x , 0x . ln 1, 0x x x
1.
(1) ( ( )) 0 ( ) 1h G x G x G1
,3e
lim ( )x
G x
, 0 1x : 0( ) 1G x (G
1
3 ,e