Unit 3, Lesson 3Mrs. King

Function rule: an equation that describes a function.

Function notation: when you use f(x) = instead of y =.

A function may be evaluated at different values of x by substituting the x-values into the function. For example, to evaluate the function defined by f (x)=2x at x=5;

The names of functions are given by either lowercase or uppercase letters.

3121 f

51 f 30 f

3020 f

33 f

3323 f

421 f

32 21

21 f

100 21 g

10 g 02 g

122 21 g

14 g

144 21 g

22 g

122 21 g

x 8 – 3x f(x)

1 8 – 3(1) 5

2 8 – 3(2) 2

3 8 – 3(3) -1

4 8 – 3(4) -4

Make a table for ƒ(t) = 0.5t + 1. Use 1, 2, 3, and 4 as

domain values.

t 0.5t + 1 f(t)

1 0.5(1) + 1 1.5

2 0.5(2) + 1 2

3 0.5(3) + 1 2.5

4 0.5(4) + 1 3

2

0

2

4 5

35

25

15

Evaluate the function rule ƒ(g) = –2g + 4 to find the

range for the domain {–1, 3, 5}.

The range is {–6, –2, 6}.

ƒ(g) = –2g + 4ƒ(5) = –2(5) + 4ƒ(5) = –6

ƒ(g) = –2g + 4ƒ(–1) = –2(–1) + 4ƒ(–1) = 6

ƒ(g) = –2g + 4ƒ(3) = –2(3) + 4ƒ(3) = –2

Find the range of the function ƒ(g) = 3g – 5 for the domain {–1.5, 2, 4}.

{–9.5, 1, 7}