Whats a Function

1
Whats a Function?

• First of all what does the word relation mean to
  you?
• A relation in math is a group of ordered pairs,
  just like your aunt and uncle.

2
Whats a Function?

• A relation in math is a group of ordered pairs.
• A function is a relation in which no two ordered
  pairs have the same x-value.

3
Whats a Function?

• A function is a relation in which no two ordered
  pairs have the same x-value.
• (3,2) , (4,5) , (6,-1) , (0,2)is a function
  because all the x-values are different

4
Whats NOT a Function?

• A function is a relation in which no two ordered
  pairs have the same x-value.
• (-3,2) , (4,5) , (6,-1) , (4,2)is NOT a function.

5
Whats a Function?
Y
X
6
Whats NOT a Function?
Y
X
7
Whats a Function
Input
function
Output
8
Whats a Function
The value of y depends on x
x
function
Output
y
9
Whats a Function
1
3x 2
5
Output
10
Whats a Function
2
3x 2
?
8
Output
11
Function Notation

• (x,y) is a solution of y 3x 2.
• (x, f(x)) is a solution of f(x) 3x 2.
• In other words f(x) is the same thing as y.

12
Function Notation

• If x 1 andf(x) 3x 2, then
• f(1) 3(1) 2
• f(1) 3 2
• f(1) 5

Remember
13
Whats a Function
1
3x 2
5
Output
14
Function Notation

• If x 2 andf(x) 3x 2, then
• f(2) 3(2) 2
• f(2) 6 2
• f(2) 8

15
Function Notation

• If x 5 andf(x) 3x 2, then
• f(5) 3(5) 2
• f(5) 15 2
• f(5) 17

Your Turn
16
Function Notation

• If x 1 andf(x) 3x2 2x - 1
• f(1) 3(1)2 2(1) - 1
• f(1) 3 2 - 1
• f(1) 4

17
Function Notation

• If x 2 andf(x) 3x2 2x - 1

Your Turn

• f(2) 3(2)2 2(2) - 1
• f(2) 12 4 - 1
• f(2) 15

18
Find the Mean, Median, and the Mode and then
construct a Box Whisker Plot

• 30, 34, 46, 26, 44,24, 30, 26, 20, 40,,36, 28,
  45, 20, 18

19
Mean 31Median 30Mode 20, 26, 30

• 18, 20, 20, 24, 2626, 28, 30, 30, 3436, 40, 44,
  45, 46

20
Box Whisker Plot
46
18
30
40
24

• 1st Quartile 24
• 2nd Quartile 30
• 3rd Quartile 40