1. Function Notation 2.3 – Fun functions 2.3 Function Notation I can:
Use Function Notation to evaluate function values.

2. (Not in your notes) Guess My Rule: What is this machine doing?4 12
x + 2 -4
x + 2 10 -6 2 x x y 2 4 10 12 -6 -4 x
x + 2

3. Guess My Rule: What is this machine doing?
-50 15 5x 1 x 5x
1/5
-10 3 x y 3 15
-10
-50 1
1/5 x 5x

4. Guess My Rule: What is this machine doing?21 -1 9
2x+1 10 -1 x
2x+1 4 x y 4 9 -1 -1 10 21 x
2x+1

5. Recall: x y
Definition of a function: each __is paired with only one __
x is called the _________
y is called the _________
input
Each input gives its own output
output x y f
Function Machine

6. x Function Notation: f(x) = 2x + 5 f(x) say “f of x”
means the same thing as “y”
y = 2x + 5
f(x) = 2x + 5
f(x)
say “f of x”
f(x) tells what to do with _____
You can use other letters for other “rules”. . .
g(x), h(x), etc… x

7. Writing “stuff” in function notation
Ex 1. Find f(3)
Before:
y = 2x Find y if x = 3
Now:
If f(x) = 2x + 5, find f(3)

8. Ex 2. Suppose g(x) = 10 + ½ x. Find:
= 10 – 2 =
= 8
= 15.5
g(-4) = 8
g(11) = 15.5

9. Your Turn: Suppose f(x) = –3x + 8. Find: f(4) f(–2) f(0)
= 6 + 8
= –12 + 8
= 0 + 8
f(–2) = 14
f(0) = 8
f(4) = –4

10. Hmmm…with powers?? Ok!
Example 3. Suppose f(x) = x2 – 5 Find… f(2) f(-1)
f(-1) = (-1)2–5
f(2) = (2)2–5
= 1–5
= 4–5
POSITIVE 1!
f(-1) = -4
f(2) = -1

11. A cubed?? NO WAY!
Example 4. Suppose j(x) = x3 + 1 Find… j(3)
f(3) = (3)3+1 =
f(3) = 28

12. Are you a Master? = 3(–5)2 + (–5) – 1 = 3(25) + (–5) – 1 = 75 – 5 – 1
If f(x) = 3x2 + x – 1, then find f(-5).
= 3(–5)2 + (–5) – 1
= 3(25) + (–5) – 1
= 75 – 5 – 1
= 69

13. Vocab filler
Function Notation