9 - + 3 - 3 + 2 + 1 - 2( )( )- 3( )( )- - 2 + 1 - 2 +1( )( )-...

2

- 9 -

+ 3

- 3 + 2

+ 1

- 2

( )( )

_{- 2}

_{- 3}

( )( )

-

- 2

+ 1

- 2

+1

( )( )

_{- 2}

_{- 3}

( )( )

_{- 3}

_{- 2}

⁼

_-3

S u t m: OÀN TI N TRUNG - THCS Hoàng V n Th - N