( ) 2f x x

, 2( )f x x

,

5 4( ) 3 5 2 7f x x x x

, ( ) 3f x

,

1( )f x

x

1( )f x

x

1(5)

5f

1( 5)

5f

1(0)

0f

1( )f x

x

3( )

2 8f x

x

2 8 0x 4x

( )f x x

( )f x x

(4) 2f (0) 0f

( 1) 1f

( )f x x

0x

6( ) 2 8f x x

2 8 0x

4x

3( ) 5 7f x x

( ) 10A x x