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MN: TON 8
Thi gian: 120 pht (Khng k thi gian giao )Bi 1( 2,0 im): Phn tch a thc sau thnh nhn t
a) ( x2 + y2)2 - 4x2y2b) (x-2)(x-1)(x+1)(x+2) - 10
c) x2- 4x -5
Bi 2( 1,5 im): Thc hin php tnh
a)
b)
Bi 3(1,5 im):
a) Chng minh:
b) p cu a thu gn phn thc:
Bi 4( 3,5 im): Hnh thang ABCD (AB // CD) c hai ng cho ct nhau ti O. ng thng qua O v song song vi y AB ct cc cnh bn AD, BC theo th t M v N.
a, Chng minh rng OM = ON.
b, Chng minh rng .
c, Bit SAOB= 20082 (n v din tch); SCOD= 20092 (n v din tch). Tnh SABCD.Bi 5(1,5 im): Cho 2x2+2y2 = 5xy v 0< x < y. Tnh gi tr ca
--------------------- Ht -----------------------
UBND HUYN KIM SNPHNG GIO DC V O TO
HNG DN CHM THI CHN HSG
MN: TON 8
Cup nim
1a) a/=
0,5
b/
0,75
c/ = x2- 5x +x -5 = x(x - 5) +( x - 5) = (x - 5)(x + 1)
0,75
2a/
0,75
b/
0,75
3a/
EMBED Equation.DSMT4 0,75
b/
0,75
40,5
a/ Lp lun c ,
0,5
Lp lun c
0,25
OM = ON
0,25
b/ Xt c (1), xt c (2)
T (1) v (2) OM.()
0,5
Chng minh tng t ON. 0,25
t c (OM + ON).
EMBED Equation.3
0,25
c/ ,
EMBED Equation.3
EMBED Equation.3
0,25
Chng minh c 0,25
Thay s c 20082.20092 = (SAOD)2 SAOD = 2008.20090,25
Do SABCD= 20082 + 2.2008.2009 + 20092 = (2008 + 2009)2 = 40172 (n v DT)0,25
5
1,5
--------------- HT ---------------
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