de hoc sinh gioi huyen toan 6 nam 2018 2019 phong gddt nam nhun lai chau

h."-NHI]N

PHONG GD&DT NAM

DE THI CHQN HOC SINH GIOI CAP HUYEN
Nim hgc 20t8-2019

M6n thi: Torln 6
Ngdy thi: 1310112019
Thoi gian.ldm bdi: 150 phrit

DE THI CHiNH THUC
(Di thi gim 0ltrans)

(Kh6ng k€ thdi gian phdt d€)
DA bni

CAu 1: (4,0 tli6m). Thuc hi6n phdp tinh
a)

155.155

-

155.41

114

b)

2to

.s5

+

210.26

28.27

c) 134- {150:50+ [120: 4+25-(12+ l8)]]
d) 100: {2s0: [450-( 4.53 -22.2s)]\
CAu 2: (4,0 tli6m). Tim x, bi5t

a) zs**1

:343

b)

7.7

c)

l2x- sl= t3

d) 11-

s6 tu nhi6n

x lon nh6t sao cho 198 + x vit270

-x

ddu chia h6t cho x.

CAu 3: ( 4,0 tli6m). So srinh

a) 1255 vit251
b) 2'm vd 10248

c)

222333 vit333222

d) 32" vd 23'(voi n e N-)
CAu 4: (6,0 tti6m).

Cho doan theng OC = 9cm vd di,5m
OA = 6cm.

A nim gi&a 2 di6m O vd C sao

cho

a) Gpi B Ii trung di€m cria OA, rinh dQ ddi do4n th6ng BC.
b) Chtmg t6 rihg A ld trung di6m cta doan thing BC.
c) Goi I

Ii

trung di6m cria doan thing OC. H6i I c6 ld trung di6m cta doan
thing AB kh6ng? Vi sao?

CAu5: (2,0tli6m).Tinht6ngd6ys6sau:

A= l+

7 +72 +73 + ...+72,',,,

---------u6t-----_
(Thi sinh kh6ng duoc si'd4ng tdi liQu, Gidm thi coi thi kh6ng giai thich gi
theml
U1


AL-.'
PHONG GD&DT NAM NHUN

xi

Ciu

noc oB ruI cnixn rnrlc
rur cHeN Hec srNH Gror cAr uuvpN
Nim hgc 2018-2019
M6n thi: Torln 6

Hufn g din ch6m

Y

Di6m

155.155-155.41

l14
155(155

-

0,5

41)

tt4

a

0,2s

155.114

114

0,25

= 155

2".55 +

2t0.26

28.27

_2'o(55

+ 26)

0,25

^8.1
1

b

210.81

0,25

n8 rl
2.3

(4,0d)

210.34

0,2s

a8 r]

^/.

.3

-22.3 -12

0,25

134- {150 : 50 + [120 :4 + 25

:r34 -[3 + (30 +25 - 30)]
:134

-

-

(12

+ 18)]]

(3 +25)

:t34-28

: 106
100 :
[ 450 - ( 4.5'- z'?.25)]\
: 100{250:
: {2s0 : [ 4s0-( 4.t2s - 4.25))]

d

:
:

450-( 500- 100)]]
100: [250: (450-400)]:100: (250:50)
=100:5=20
100 : {250 : [

0,25
0,25
0,25
0,25
0,25
0,25

o?s
0

?5

25<5'<125

I
(4,0d)

=52

0,5

<5* <53

0,25

=2Do d6

x:2;x:3

0,2s

1/3


7.7 "*t

:343

: 73
)x+ 2:3
= x:1
>'l**2

b

0,5
0,25
0,25

lzx- sl= t:

*TH1:2x-5=13
c

0,25

+ 2x= 13+5=2x:18+x:9
+2x:-13+5=2x:-8+x=4
V{y x:9 ;x:4
Tac6(198+x)ix +198i x
(270-x)ix+270:x
*TH2:2x-5:-13

Md x l6n nh6t n€n x le UCLN (198;270)
d

lg8:2.32.11
270 :2.33.5
= tjctN (t98; zto) =2.32 = t8

a

> 257

vir 10248
Ta c6: 10248: 12r)8:
Vi 100 > 80 + ztoo >

0,25

0,25

0,2s
0,25
0,25
0,25

515

:5ta
Vi15>14+5r5>5ra
1255

o)5

0,2s

257 :15217

N6n

0,25

0,25

:

vOv 18
l25s vit257
Ta c6: 1255: 153;s=

0,25

2t0o

b

N6n

2roo

>

0,25
0,s
0,25

280
280

10248

222333 vit333222

3

(4,0d)
c

Tac6:222333 -(222')"'

333222: (3332)"'
Ta sE so sitnh2223 vd,3332
Ta c6 2223 = (2. I 1 l)3 23. I

:

0,2s
1

13

:

8.1 I l3 = 888. I I l2

3332: (3.1I l)2:32.t l12:9.1112
Vi888>9 =+ 888.1112>g.lll2 =2223 >3332
Do d6

222333 >333222

vd z3n
Ta c6: 32n:132;n=
23n=123yn:gn

0,25
0,25
0,25

32n

d

9n

Vi9>8+9n>8"(VineN-)
Nen

32n

>

23n

2t3

0,25
0,25
0,2s
0,25


05

BIA

o

C

Vi B ld trung di€m cria OA n6n
a

Oe:

(cm)
!=!=z
22

Ta c6 A nim gifra O vd C, mir B nim gita O vd A
< OA ( 3 < 6), n€n B nim gita O vd C
+OB + BC: OC hay 3 +BC:9

vi OB
05

+BC:9-3:6(cm)

05

I

Di€m A nim gita y16 n6n 661- ag
:9 - 6: 3 (cm)
Hay 6 + AC :9
=AC
4

L4i c6: B ld trung diiim crla OA n6n ne

(6,0d)
b

=AB: AC:3 (cm) (l)

: OC

: $ = ! =:1cm)
22

0 5

0,5
0,5

Vi I ld trung di6m cria do4n thing OC n6n I nim gita O
vd C, md A vd B thuQc 2 tia d6i nhau chung g5c I n€n
di6m I nim gita hai
0 5

oB + BI

0 5

:or:

+=?=a,s(cm)
22

:

Hay 3 + BI 4,5+BI -- 4,5 -3 1,5 (cm)
Tuong tg ta c6
1,5 (cm)
+ IA: IB :1,5 (cm), mir I nim"giira hai tti6m A
Vdy I ld trung di6m cria doan thing AB.
NhAn c6 2 v6 cria A vdi 7 ta duoc:
7A:7(l +7 +72 +73 + ...+72ooi)
+72 + 73 +...+ 72008)
Md
1+7 +72 +73 + ...+72'n7

IA:

(2,0d)

0 5

M4t khric B vd C thu6c 2 tia d6i nhau chung g6c A n6n
di5m A nim gita hai diiim B vd C (2)
Tir (l) vd (2) suy ra A ld trung diiim cria doan thing BC.

:

5

05

:e

A:

NCnTA-A=6A.

VAvA: t -l

-72008

-l

-2008

05

vi

B.
0,5
05
05

05
o5

6

J/ J