ĐỀ KHẢO SÁT ĐẦU NĂM - TOÁN 8, CÓ ĐÁP ÁN CHI TIẾT



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!"#$%&'(')*+,-.,'/01%234
56
78  9:;%<*=>1>*=2*(?,?'@3;%A;>'=B*(3CDE;=>1>*=F
?,G.,'+,-
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 
 
−



!
−
"

!
#$!%!
HIK7&'()*
=
a c
b d
+,- -/012345()*

=
a b
c d
"
=

a d
b c
#
=
d a
b c
%
=
a b
b c

HIL767*
 

8 4 9

:.;
"# %!
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⊥
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⊥
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⊥
. # D.%
 .≡
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HIO"K.<F?<3@4không l 3FK1

LL "MLJL!
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7PQ$R='S-4
5,'J$KT0='S-4#<1*
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!
= − − + +
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O8 8 8 I 8
!
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P8 N8 O8= +
. #*Q5R*P80E:)
5,'K$J='S-ST.*NG
!8  !8  

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+ −
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−
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− + −
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≠ ±

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!
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5,'L$L='S-4"
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.#*V"UGVU"
#*
UV %
V %#
=
5,'M$JT0='S-4<X3Y- -/-Z012Q[\0)
! ! !
. L  ./L / Z= = =

#*5R
   
   
 .  / 
.  / Z Z
+ + +
=
+ + +

$$$$$$$$$$$$$$$$$$$$$$$$$U]&$$$$$$$$$$$$$$$$$$$$$$$$$
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
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
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#@  !   M
611 "  %  " #
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5,'J!

!
P8 N8 O8 8 H= + = +

.&:P8G
!
8 H 2+ >
+,T8/<:P80E:)
5,'KSTNG
!8  !8  

!8  !8  M8 
+ −
 
−
 ÷
− + −
 
+,8
≠ ±

!
&:
( ) ( )
( ) ( )

( )
! !
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M
N
!8  !8   !8 
+ − − + −
= × = ×××××=
− + +

5,'L
∆
"U 
∆
#"2-I 
I
A
C
B
H
D
.^
∆
"U:"V@1
V "
VU "U
⇒ =

⇒
V"UGVU"

^
∆
"#:"%@1
% "

%# "#
⇒ =
2-! 
#:
∆
"U 
∆
#"&Z<@
" "U
!
"# "
⇒ =
2-! 
&'+!
AD BH
DC AB
⇒ =

% "U

%# "
⇒ =
2-! 
_F:"V@1
∆

"U
IH BH
IA AB
⇒ =

VU "U

V "
⇒ =

&'+
UV %
V %#
⇒ =
2-! 
`aB2-! 
5,'M-2
&'
! ! !
. L  ./L / Z= = =
345
 .  /
.  / Z
= = =
2-! 
6b
 .  /
0  .0 0- /0-Z /0
.  / Z
= = = = ⇒ = = = =

2-! 
&:
            

           
 .  / .0 0 /0 Z0 .  / Z 0
0
.  / Z .  / Z .  / Z
+ + + + + + + + +
= = =
+ + + + + + + + +

&F:

  .  /
   0000 0
Z .  / Z
= = =
!
&'+!345


. /
. / Z Z
+ + +
=
+ + +
2-
HS lm theo cỏch khỏc m ỳng vn cho im ti a.
Cõu 8. "

=
x y
7 3
+8c4G2&B=d8+4
8GM -4G "8GII-4G #8GH2-4G2%8G

II-4G


II Tự luận ( 8,0 điểm )
Bài 1 ( 2,0 điểm ) Điểm thi khảo sát chất lợng đầu năm môn Toán của lớp 8A đợc ghi lại nh sau:
8 6 10 7 6 8 10 3 8 6 5 7 8
5 10 9 7 5 8 6 7 3 7 8 9 8
a. Dấu hiệu ở đây là gì?
b. Tính số trung bình cộng của dấu hiệu.
5,'K!-2#<1*
!

!
!
P x x x x= + +
+
!

I
!
Q x x x x= + +
&B
M x P x Q x= +
/ #*Q5R*P80E:)

5,'L-2#<1"#+EF:"G-#G
&"#
. &5eF#f4g3<<gG-5eY"f4%3<<
%G"#*5R
BEC DEC
=
c. Chứng minh rằng DE đi qua trung điểm của cạnh BC.
Bài 4 (1,0 điểm ) cho năm số a, b, c, d, e khác 0 thỏa mãn điều kiện
! ! !
L Lb ac c bd d ce= = =
.
Chứng minh rằng:


a b c d a
b c d e e
+ + +
=
+ + +
.
hết