1. Combinations of Functions
Sec. 2.6
Combinations of Functions

2. Arithmetic Combinations of Functions
Sum, Difference, Product, and Quotient of Functions
Sum (f + g)(x) = f(x) + g(x)
Difference (f – g )(x) = f(x) – g(x)
Product (fg)(x) = f(x) • g(x)
Quotient (f/g)(x) = f(x)/g(x)
Domains: consist of all real numbers common to both domains.

3. Ex. 1 p. 229 f(x) = 2x + 1 g(x) = x2 +2x – 1 Find (f+g)(x)
Find (f – g)(x) then evaluate when x = 2

4. Any restrictions on the domain of f and g must be considered.
Ex. 6 Quotient
f(x) = √x g(x) = √(4-x2)
(f/g)(x) b) ( g/f)(x)

5. Ex.
f(x) = 3x g(x) = 2x
a) Find (f + g)(-1) b) (f/g)(2)

6. Composition of Functions
f(g(x)) denoted (f ◦ g)(x)
Means some value x is put in the function g, then the solution to that is placed in the function f.
The domain of f ◦ g is the set in the domain of g such that g(x) is in the domain of f.

7. Ex. 7
f(x) = x + 2 g(x) = 4 – x2 a)Find (f ◦ g)(x) b) (g ◦ f)(x)

8. Ex
Find (f ◦ g)(x) for f(x) = 3x2 + 2 and g(x) = 2x