1. Function notation & evaluating functions
Algebra I ~ Unit 2, Lesson 3

2. Function Notation
Traditionally, functions are referred to by the notation f(x), which is read "f of x" or "f  as a function of x". 
[In this situation, the parentheses do not mean "multiplication".]
The letter f need not be the only letter used in function names.  Function names may also be g(x), h(x), A(x), C(a), or any letters that clearly identify the function being used.

3. x is the independent variable
this is the
function’s rule
f(x) is the dependent variable
x is the independent variable
f is the function name

4. Evaluating Functions
To evaluate a function, simply replace (substitute) the function's variable with the indicated number or expression.
Find the value of
R(v) = v3 + 3v2 – 5v – 6 when v = -2.
A function is represented by f (x) = 2x + 5.
Find f (3).

5. Evaluating Functions Use the graph to find the value: f(1) f(19)
x when f(x) = 20
f(0) + [x when f(x) = 10]
f(25)
3 · f(13)
f(21) - [x when f(x) = 0]
when x =1, f(x) = 7
when f(x) = 20, x = 20
when x =19, f(x) = 18
when x =2, f(x) = 6
6 – 1 = 5
when x =9, f(x) = 1
= 23
when x =25, f(x) = 15
= 3 · 7 = 21
= 11