DE THI HSG TOAN 9 _ 2012 - 2013 TP HA NOI










4 3 2
P(x) 4x 11x 2ax 5bx 6
= − − + −


2
Q(x) x 2x 3
= − −


(
)
(
)
2013 2012 2011 2013 201 2 2011
P a 8a 11a b 8b 11b= − + + − +

 !"#
a 4 5, b 4 5
= + = − 

$%&'()*

2 2
2 2
6x y xy 5x 5y 6 0
20x y 28x 9 0

− − + + − =


− − + =



+,-+%.'()*
2 2
6 x 10y 2xy x 28y 18 0
+ + − − + =


/()
a, b, c
%.
1 2 3
3
a b c
+ + =

*
2 2 2
2 2 2 2 2 2
27a b 8c 3

2
c(c 9a ) a(4a b ) b(9b 4c )
+ + ≥
+ + +



ABC
0 0123'(45
(O)
 
AB AC
<
 (4
AD, BE, CF
!
ABC
6'78$19:(4;
EF, CB

<(4;
AI
=
(O)
7>#?
@
A, M, F, H, E
AB,3(45
$1C:
BC


M, H, N
;

BM.AC AM.BC AB.MC
+ =



2013

1 2 2 013
A , A , , A (45
(
)
O, 1
DEAB36';
  , (4 5
(
)
O, 1
 02  :F 0   (G 3  >  
1 2 2013
MA MA MA 2013
+ + + ≥

H






