Bài tập 1:  a) f x x ( ) = - (1 3)5 b) f x x x x ( ) = - + + 4 2 200
c) f x x x x ( ) = - + - 3 2025 4 3 d) f x x x ( ) 3 2 2 7 5
x
= - + +
e) f x x ( ) 4
x
= - f) f x x x x ( ) = - + + 7 5 3 2 3
g) f x x x ( ) = + - ( 1 2 )( ) h) ( ) 3 5
1 2
x
f x
x
+
=
- +
i) ( ) 2
1
x
f x
x
-
=
-
j) ( ) 1
1
x
f x
x
-
=
+