Answer:The Algebra of Functions
Like terms, functions may be combined by addition, subtraction, multiplication or division.
Example 1. Given f ( x ) = 2x + 1 and g ( x ) = x2
+ 2x – 1 find ( f + g ) ( x ) and
( f + g ) ( 2 )
Solution
Step 1. Find ( f + g ) ( x )
Since ( f + g ) ( x ) = f ( x ) + g ( x ) then;
( f + g ) ( x ) = ( 2x + 1 ) + (x2
+ 2x – 1 )
= 2x + 1 + x2
+ 2x – 1
= x
2
+ 4x
Step 2. Find ( f + g ) ( 2 )
To find the solution for ( f + g ) ( 2 ), evaluate the solution above for 2.
Since ( f + g ) ( x ) = x2
+ 4x then;
( f + g ) ( 2 ) = 22
+ 4(2)
= 4 + 8
= 12
Example 2. Given f ( x ) = 2x – 5 and g ( x ) = 1 – x find ( f – g ) ( x ) and ( f – g ) ( 2 ).
Solution
Step 1. Find ( f – g ) ( x ).
( f – g ) ( x ) = f ( x ) – g ( x )
= ( 2x – 5 ) – ( 1 – x )
= 2x – 5 – 1 + x
= 3x – 6
Step 2. Find ( f – g ) ( 2 ).
( f – g ) ( x ) = 3x – 6
( f – g ) ( 2 ) = 3 (2) – 6
= 6 – 6
= 0
Explanation: