hoc360.net - + a. có y x x r r · 2019. 1. 7. · câu 77. y mx m m x4 2 4 33 2 2 0 0 4 3 ;0 1;3 0...
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+ A. Có 2' 3 0y x x R R . Hay nói cách khác, hàm
+ 2 3 3 0b ac
2 3 9 0b acCâu 49.
2' 3 12 4y x x .2' 0 3 12 4 0y x x .
1 2,x x ' 0y .
1 2 4x x .
Câu 50.2' 3 6 3 ( 2)y x x x x
0' 0 3 ( 2) 0
2
xy x x
x
(0) (2) 4CD CTy y y y .
Câu 51.2' 3 2y ax bx c
'(0) 00
(0) 0
yc d
y
+ ( 1; 1)A , ta có:
'( 1) 0 3 2 0 2
( 1) 1 1 3
y a b a
y b a b3 22 3y x x .
Câu 52.
2 3 5 0b acR
Câu 53.
+ 02
b
a0a 0ab .
Câu 54.2 23 0 4 (4 1) 0b ac m m
2 1(2 1) 0
2m m .
Câu 55.
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3 2' 4 8 4 ( 2)y x x x x
20
' 0 4 ( 2) 02
xy x x
x
2 7CDx y .
Câu 56.
+ 2 3 25 0b ac4 23 2y x x
+ C. Có 2
2
2 1' 0 \ 0
3
xy x R
x
+ D. Có 5 3' 2017.6 2016.4y x x . Xét ' 0 0y x
Câu 57.
Ta có 3
4
2 2'
1 4
xy
x x. ' 0 1 (1) 2y x y
Câu 58. n A
Ta có 2' 3 4y x x a
(1;3)A , ta có:
'(1) 1 0 1
(1) 1 3 3
y a a
y a b b
.Câu 59.
2' 3 6y x x
0' 0
2
xy
x
Ta có: 2(0) 2; (2) 6 2 2a y b y a b .
Câu 60.
+ 1 2 3 0x x x .
Câu 61.
2' 3 3 0y x1
1
x
x
1xCâu 62.
3' 4 4 0y x x0
1
x
x
4Cy
Câu 63.
22' 4 4 2 0,y x x x x R
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Câu 64.
2' 3 6 0y x x0
2
x
x
Câu 65.
Câu 66.3' 4 2 1 0y mx m x
2
2
02 2 1 0
2 1
xx mx m
mx m
1 1 0
0
mm m
m4 2y ax bx c a và b
0ab
Suy ra : 1
1 00
mm m
m
Câu 67.
2' 3 4 3y x x m
5' 0 4 3 3 0'
3m my
Câu 68.
2' 2 1y x mx m
" 2 2y x m
2x khi : ' 2 0 4 4 1 0 1
4 2 0 2" 2 0
y m m m
m my
m ).Câu 69.
Câu 70.
2' 4y mx x m
ycbt 2
'' 0 4 00 2
00
y mm
mm
Câu 71.2 2 6y x mx m
0y
2 26 0
3
mm m
m
Câu 72.
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23 2 6y m x x m
0y
2
2 23;1 \ 2
3 12 3 0
m mm
mm m
Câu 73.2 2( 3) 4 3y x m x m
0y 1 2,x x 1 21 .x x
2
1 2 1 2 1 2
1 2 1 2
3
13 4 3 0 3 1 0
7 71 1 0 1 0 3
2 22 2 2
m
mm m m m
x x x x x x m m
x x x x m
Câu 74.2 2 2
2
2( 2) 3 1
2 2( 2)
y x m m x m
y x m m
2x khi:2
2
2 0 4 3 03
2 0 0
y m mm
y m m
Câu 75.2 2( 1) 3 2y mx m x m
0y 1 2;x x 1 22 1.x x
2
1 2 1 1
2 21 2
1 21 2
0 00
6 6 6 61 1 1 11 3 2 0 2 2 2 2
3 2 3 4 3 4
2 22 1
3 2 3 22 1 3 4 2
m mm
m mm m m
m m mx x x x
m m m
m mmx xx x
m mmm mx x m m
x xm m m m
2
2
3
m
m.
Câu 76.
0m2y x 0m
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34 2 1y mx m x
110
0
mm
mm.
0
1
m
m
Câu 77.3 24 2 4 3y mx m m x
2
00
;0 1;34 3;0 1;30
mm
mm mm
m
.
Câu 78.3 2
2 2
4 4
0 4 0
y x m x
y x x m
4 40;1 , ;1 , ;1A B m m C m m
ABC A .
ABC 2 8 0. 0 0
1
mA AB AC m m
m.
3
1 08
b
a.
Câu 79.3
2
4 4 1
0 4 1 0
y x m x
y x x m
20; , 1; 2 1 , 1; 2 1A m B m m C m m
ABC A .
ABC . 0A AB AC
2 2 4 3 2 01 ( 2 1) 0 4 6 3 0
1
mm m m m m m m
m.
0m
+) Cách 1: M BC M, ABC A thì .
+) Cách 2: 2 2 2BC AB AC .
+) Cách 3: 0cos , cos45BA BC .
3
1 08
b
a.
Câu 80.
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3
2
4 4
0 4 0
y x mx
y x x m
4 4 2 4 20; 2 , ;m 2 , ;m 2A m m B m m m C m m m
ABC A .
ABC 4
3
04
3
mAB BC m m m
m.
3 3m
3
3 08
b
a
32
3 08
m 3 33 3m m .
Câu 81.
Ta có: 3 3y x x
(1; 2); ( 1;2)A B . Nên ta có 2 5AB .
Câu 82.
Ta có: 4 212 3
4y x x .
( 2; 1); (0;3); (2; 1)A B C .
B . (0; 1)H AC .
Nên 1 1
. .4.4 82 2
ABCS BH AC .
Câu 83.
Ta có :
0y 2 2 1 0 1m m m .
Câu 84.
.
Ta có :2
3 2 2 9' 4 2 9 4 ( )
2
my mx m x mx x
m.
3 'y có 32 9
02
m
m
2 9 0m m0 3
3
m
m.
0 3
3
m
m.
Câu 85.
TH1: 2 3
2y x
TH2:
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3 2' 4 1 2 4 12 1
my m x mx m x x
m.
i 'y
x
4 1 0
02 1
m
m
m
.
m .Câu 86.
Ta có .
0y
m ).
.
.Câu 87.
Ta có .2' 0 0 *y x m
PT * 0 **m
;1 2A m m m , ;1 2B m m m
Tam giác OAB O 3 1. 0 4 1 0
2OAOB m m m
1
2m .
Câu 88.
Ta có t
.
Câu 89.
Ta có : 2 2 2 2' 2 2 2 3 1 2 3 1y x mx m x mx m ,
2 23 1g x x mx m 213 4m
'y g x
0
2 13
13
2 13
13
m
m
. (1)
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1x , 2x g x -ét, ta có 1 2
21 2 3 1
x x m
x x m.
1 2 1 22 1x x x x 23 2 1 1m m 23 2 0m m
0
2
3
m
m.
2
3m
Câu 90.
2 2' 3 6 3 1y x mx m
m
1 2
21 2
2
. 1
x x m
x x m22 2 2
1 2 1 2 7 2 3 1 7x x x x m m m= ±2.
Cách 2 : 2 22 1x mx m =01
1
x m
x m.
2 22 21 2 1 2 7 1 1 1 1 7x x x x m m m m 2m .
Câu 91.
3' 4 1 6 0y m x mx (*)
TH1 ' 6 0y x hay x= 0 , '' 6 0y
TH2 1m
(*) 2
0
3
2 1
x
mx
m
.
1 0
0 130
2 1
m
mm
m
.
0;1m .
Câu 92.
3 2' 4 4 1y x m x
' 0y2 2
0
1
x
x m.
1m
0; 1A m
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2 4 21 ; 2B m m m m
2 4 21 ; 2C m m m m
22 1 ;0BC m
BC : 4 22 0y m m m
4 2,BC 2 1d A m m , 22 1BC m
2 4 21. [ , ] 1 2 1
2ABCS BC d A BC m m m =
521 1m
.
2 4 21 ; 2 1AB m m m
2 4 21 ; 2 1AC m m m
1,
2AB AC = 2 4 21 2 1m m m =
521 1m
.Câu 93.
2' 6 6 3y x m x
0 0
3
x
x m
0;11 3A m
3 23 ; 9 24 16B m m m m
33 , 3AB m m .
AB : 2
3 11 3 0m x y m
, ,A B C
Hay : .
:
2
3 26 6 3 12 6 3'. ''
2 3 3 11 318 36
x y x x yy yy x y x y
a: Cacl x i , 1000y
. Hay : 2989 994009y x
, 2
994009 3m2
3 11 3 0m x y m
A,B,C thHay : .
Câu 94.
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2' 3 3y x m
' 0x m
yx m
0m
; 2 2M m m m
;2 2N m m m 2 ;4MN m m m
: 2 2 0mx y
y chia cho y )
Ta có : 1 1 1
. .sin sin2 2 2
IABS IA IB AIB AIB
090AIB2
,2
d I MN2
2 1 1
24 1
m
m
31
2m
:
2
36 3 12'. ''
2 3 218 18
x y xy yy x yx
a: Cacl x i , 1000y
. Hay : y=,
,A B là : 2 2y mx hay 2 2 0mx y
Câu 95.
Ta có : 26 6 1 6y x m x m
1' 0
xy
x m
à :
Ta có : 1;3 1A m 3 2; 3B m m m
AB là : 2
1k m
AB 2y x 1k0
2
m
m
:
2
3 26 6 1 6 12 6 1'. ''
2 3 1 618 36
x y x y x yy yy x y x yx
a: Cacl x i , 1000y
. Hay : 1001000 9980001.y x
AB là : 22 1y m m m x