Page 82 - Math Course 3 (Book 1)

Using Functions
Mo. 3

Lesson 1 Let’s Begin

KEY CONCEPTS:
1. Determine whether relations are functions. Ordered Pairs and Tables as Functions
2. Use functions to describe relationships
between two quantities.
Examples

MO. 3 - L1a Determine whether the relation is a function.
Explain.
Determining Functions {(–3, –3), (–1, –1), (0, 0), (–1, 1), (3, 3)}

No; –1 in the domain is paired
Answer
Vocabulary A-Z with both –1 and 1 in the range.
Let us learn some vocabulary
Determine whether the relation is a function.
Explain

Function x 7 6 5 2 –3 –6
y 2 4 6 4 2 –2
is a special relation in which each member of the
domain is paired with exactly one member in the
range. Yes; each x value is paired with
Answer
only one y value.
{(–2, 1),(–4, 3),(–5, 4),(–9, 7)}

–2 1 Use a Graph to Identify Functions
–4 3
–5 4 Examples
–9 7
Determine whether the graph is a function. Explain.

vertical line test

Another way to determine whether a relation is
a function is to apply the vertical line test to the
graph of the relation.

Use a pencil or straightedge to represent
a vertical line.

y

Answer Yes; it passes the vertical line
0 x test.

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