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

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.

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

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).

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 8 + 15 = 23 when x =25, f(x) = 15 = 3 · 7 = 21 19 - 8 = 11