1. Five-Minute Check (over Chapter 1) Mathematical Practices Then/Now
New Vocabulary
Key Concept: Functions
Example 1: Domain and Range
Key Concept: Vertical Line Test
Example 2: Graph a Relation
Example 3: Evaluate a Function
Example 4: Real-World Example: Discrete and Continuous Functions
Example 5: Choose the Correct Model
Lesson Menu

2. Solve 2(c – 5) – 2 = 8.
A. –4
B. 4
C. 10
D. 20
5-Minute Check 1

3. Solve 2b – 5 ≤ –1. Graph the solution set on a number line.
A. {b | b ≤ 2}
B. {b | b < 2}
C. {b | b ≥ 2}
D. {b | b > 2}
5-Minute Check 2

4. Which algebraic equation shows the sentence four plus a number divided by six is equal to the product of twelve and the same number?
A. eans
B. eans
C. eans
D. eans
5-Minute Check 3

5. Find the slope of the line that passes through (5, 7) and (–1, 0).B.
C. 2
D. 7
5-Minute Check 4

6. Write an equation in slope-intercept form for the line that has x-intercept –3 and y-intercept 6.
A. y = –3x + 6
B. y = –3x – 6
C. y = 3x + 6
D. y = 2x + 6
5-Minute Check 5

7. Mathematical Practices
1 Make sense of problems and persevere in solving them.
2 Reason abstractly and quantitatively.
4 Model with mathematics.
7 Look for and make use of structure. MP

8. Content Standards
F.IF.4 For a function that models a relationship between two quantities, interpret key features of graphs and tables in terms of the quantities, and sketch graphs showing key features given a verbal description of the relationship.
F.IF.5 Relate the domain of a function to its graph, and where applicable, to the quantitative relationship it describes. MP

9. Functions and Continuity
Section 2.1

10. You identified domains and ranges for given situations.
Determine whether functions are one-to-one and/or onto.
Determine whether functions are discrete or continuous.
Then/Now

11. Vocabulary Review Domain Range Function Set of possible x-values
Set of possible y-values
Function
A relation in which each element of the domain is paired with exactly one element in the range

12. one-to-one function onto function discrete relation
continuous relation
vertical line test
independent variable
dependent variable
function notation
codomain
Vocabulary

13. Key Concept

14. Domain and Range
State the domain and range of the relation. Then determine whether the relation is a function. If it is a function, determine if it is one-to-one, onto, both, or neither.
Example 1

15. Domain and Range
D = {–4, –3, 0, 1, 3} The domain consists of the x- values in the points of the relation.
R = {–2, 1, 2, 3} The range consists of the y- values in the points of the relation.
Relation is a function. Each member of the domain is paired with one member of the range.
Not one-to-one. Each element of the domain does not pair with exactly one element of the range.
Example 1

16. Domain and Range
Answer: D = {‒4, ‒3, 0, 1, 3}; R = {‒2, 1, 2, 3} Each member of the domain is paired with one member of the range, so this relation is a function. It is onto, but not one-to-one.
Example 1

17. Key Concept

18. Graph a Relation
Graph y = 3x – 1 and determine the domain and range. Then determine whether the equation is a function, is one-to-one, onto, both, or neither. State whether it is discrete or continuous.
Example 2

19. D = All real numbers The graph goes from −∞ to ∞ along the x- axis.
Graph a Relation
m = 3 and b = –1 Graph the equation and use the vertical line test to determine if the equation is a function.
D = All real numbers The graph goes from −∞ to ∞ along the x- axis.
R = All real numbers The graph goes from −∞ to along the y- axis.
Continuous There are no interruptions in the graph.
Example 2

20. Graph a Relation
One-to-one and onto Each element of the domain is paired with one element of the range and each element of the range is paired with one element of the domain.
Answer: The domain is all real numbers; the range is all real numbers; the equation is a function; the function is both one-to-one and onto; the equation is continuous.
Example 2

21. Given f (x) = x3 – 3, find each value.
Evaluate a Function
Given f (x) = x3 – 3, find each value.
A. f (–2)
f (x) = x3 – Original function.
f(–2) = (–2)3 – Substitute
f(–2) = –8 – Evaluate (–2)3
f(–2) = – Simplify
Answer: –11
Example 3A

22. Given f (x) = x3 – 3, find each value.
Evaluate a Function
Given f (x) = x3 – 3, find each value.
B. f (2t)
f(x) = x3 – Original function.
f(2t) = (2t)3 – Substitute
f(2t) = 8t3 – (2t)3 = 8t3
f(2t) = 8t3 – Simplify
Answer: 8t3 – 3
Example 3B

23. Discrete and Continuous Functions
TRANSPORTATION The table shows the average fuel efficiency in miles per gallon for SUVs for several years. Graph this information and determine whether it represents a function. Is the relation discrete or continuous?
Real-World Example 4

24. Discrete and Continuous Functions
Graph the data in the table. Label the horizontal axis with the year and the vertical axis miles/gallon.
Because the graph consists of distinct points, the function is discrete.
Use the vertical line test. No vertical line can be drawn that contains more than one of the data points. Therefore, the relation is a function.
Real-World Example 4

25. Answer: Yes, this relation is a function, and it is discrete.
Discrete and Continuous Functions
Answer: Yes, this relation is a function, and it is discrete.
Real-World Example 4

26. A commuter train ticket costs $7.25. The cost
Choose the Correct Model
A commuter train ticket costs $7.25. The cost
of taking the train x times can be described by
the function y = 7.25x, where y is the total cost
in dollars. Determine whether the function is
correctly modeled by a discrete or continuous
function. Explain your reasoning.
When deciding whether a real-world situation is modeled by a discrete or continuous function, consider whether an interval of all real numbers makes sense as part of the domain.
Real-World Example 4

27. Choose the Correct Model
If a person buys 2 train tickets, it will cost $ Three tickets will cost $21.75, 4 tickets will cost $29.00, and so on. You cannot purchase 1.5 tickets or 2.25 tickets to ride the train.
Since the domain consists only of whole number, this is correctly modeled by a discrete function and the graph will consist of the set of unconnected points (1, 7.25), (2, 14.50), (3, 21.75), (4, 29.00), and so on.
Because the graph consists of distinct points, the function is discrete.
Example 5

28. Choose the Correct Model
Use the vertical line test. No vertical line can be drawn that contains more than one of the data points. Therefore, the relation is a function.
Answer: Discrete; you cannot purchase a fractional of a ticket, so the domain is the set of whole numbers.
Example 5