+ = ⇔ = −A B A B0⇔ − + = − +3 32 23 2007 3 7 2008X X X X3 2007 3 7 2008 1⇔ − + = − + ⇔ =X X X X X0

1) - DE THI THU VA DAP AN CHI TIET 10 CHUYEN09 10
Toán DE THI THU VA DAP AN CHI TIET 10 CHUYEN09 10
1)

+ = ⇔ = −

a b

a

b

0

⇔

− +

=

−

+

3

3

2

2

3

2007

3

7

2008

x

x

x

x

3

2007 3

7

2008

1

⇔

− +

=

−

+

⇔ =

x

x

x

x

x

0.25

6