4.1 an overview of relations and...
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Smart Board Notes Unit 4.notebook
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January 26, 2016
Jan 265:56 PM
Unit 4
Relations and Functions
Jan 266:25 PM
4.1 An Overview of Relations and Functions
Jan 266:27 PM
A Relation associates the elements of one set of objects with the elements of another set.
Relations can be represented with:
1. Words
2. Sets of ordered pairs
3. Arrow Diagrams
4. Tables of Values
5. Graphs
6. Equations
Jan 267:32 PM
Example 1: Consider the set years Y and the set of NHL hockey teams H such that
Y = {2010, 2011, 2012, 2013, 2014}
H = {Chicago Blackhawks, Boston Bruins, Los Angeles Kings}.
With words, we can define the relation
As a set of ordered pairs:
Note: There are many ways to describe a relations using words. Also, many different relations can exist between two sets.
Jan 267:55 PM
Note: In an arrow diagram we use ovals to represent our sets and each arrow represents how elements associate with one another.
2010
2011
2012
2013
2014
Bruins
Blackhawks
Kings
This relation in an Arrow diagram:
The Stanley cup went to
Jan 268:14 PM
Example 2: Sam Wonders if there is a relationship between the length of a person's ear and the length of their face.
Sam samples 5 of her friends and presents the following data.
Length of Ear Length of Face
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Smart Board Notes Unit 4.notebook
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January 26, 2016
Jan 268:26 PM
Sam notices a relation between the data sets.
Represent this relation in an arrow diagram:
As set of ordered pairs:
In words:
Jan 268:38 PM
As a graph:
As an equation in two variables:
Jan 271:26 PM
Problem set 1.
p. 26263 3(a), 4, 7(a,b), 8
Jan 268:41 PM
Domain Range"maps to"
When describing relations we often speak in terms of a domain and a range.
The domain is the set of first elements in a relation (i.e., a set of "xvalues" or "inputs" in a relation).
The range is the set of second elements in a relation (i.e., a set of "yvalues" or "outputs" in a relation).
Jan 2710:43 AM
We also speak in terms of independent/dependent variables.
Elements in the domain represent the independent variable (which does not depend on the variation of another variable).
Elements in the range represent the dependent variable (which depends on the variation of another variable).
Jan 2712:13 PM
Identify the independent variable and dependent variable in each of the following contexts.
Example 1: The amount of time spent studying affects the grade a student receives.
Example 2: The temperature outside affects the amount of ice cream sold.
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January 26, 2016
Jan 2712:23 PM
A function is a special type of relation where each element in the domain is paired with exactly one element in the range.
Example: the following relation is a function.
Robert Downey Jr.
Chris Evans
Edward Norton
Mark Ruffalo
Scarlett Johansson
Iron Man
Black Widow
The Hulk
Captain America
Acts as
Jan 2712:28 PM
Not all relations are functions.
But all functions are relations!
Robert Downey Jr.
Chris Evans
Edward Norton
Mark Ruffalo
Scarlett Johansson
Iron Man
Black Widow
The Hulk
Captain America
is played by
Jan 271:01 PM
Which of the following relations are functions, which are not?
423
16 4
251
894
123
7043
42
Jan 271:01 PM
Which of the following relations are functions, which are not?
{(2,4), (3,6), (4,6), (5,6), (6,12)} {(3,7), (0, 10), (3,13), (3,5), (6,16)}
Jan 271:20 PM
How to determine whether a relation is a function:
1. If any values in the domain are associated with more than one value in the range, the relation is not a function.
2. A graph that fails the "vertical line test" does not represent a function.
Jan 271:25 PM
Problem set 2
p. 270 4., 8., 9., 12.
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Smart Board Notes Unit 4.notebook
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January 26, 2016
Jan 271:43 PM
4.2 Function Notation
Jan 278:09 PM
A function can be viewed as a rule or a machine that takes input values (x) and produces output values (y).
Equations that represent functions, such as y = 4x + 3, may written using functional notation f(x).
f(x) = 4x + 3
Note: This notation can be thought of as another way of representing the yvalue.
Jan 278:55 PM
f (x)
Jan 278:58 PM
Example 1. Write the following in functional notation.
a) y = 2x + 5
b) v = 5t 2
c) p = n 2/3
Example 1. Write the following as an equation in two variables.
d) f(x) = 3x + 2
e) h(t) = 6t + 9
Jan 279:02 PM
Example 2: if p(r) = 2r + 3 determine the following.
a) p(2) b) p(3)
NOTE: An input value x and an output value f(x) can be written as ordered pair (x, f(x)).
Jan 279:37 PM
Example 3. If v(t) = 4t 7 find the value of t when v(t) = 29. Check your answer.
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Smart Board Notes Unit 4.notebook
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January 26, 2016
Jan 279:41 PM
Tom is eating popcorn at the movies. The equation P = 25m + 250 represents the amount of popcorn Tom has left after m minutes.
a). Describe the function. Write the equation in functional notation.
b). Determine the value of P(3). What does this value represent?
c). Determine the value for m when P(m) = 0. What does value this represent?
Feb 36:19 PM
TwoMinute Write!
Give an example of a any relation (other than the ones discussed in class), and explain why or why not your example is a function.
Creativity is appreciated.
Jan 2711:19 PM
4.3 Graphing and Interpreting Data
Jan 311:15 PM
Describing Graphs
Jan 313:16 PM
On a distancetime graph what do the following represent?
1. A line going upwards to the right.
2. A line going down to the right
3. A horizontal line
Jan 312:28 PM
Sketching Graphs (given a situation) A salmon is swimming upstream. For the first hour, it swims strongly and at a constant speed. For the next two hours, due to fatigue and a stronger current, it swims half as fast. It finally realizes it has passed its destination so, for the final halfhour, it stops swimming and allows the current to carry it slowly back downstream. Sketch a possible distance versus time graph to best represent the path of the salmon.
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January 26, 2016
Feb 71:33 PM Feb 71:27 PM
Speedtime Graphs
Jan 313:19 PM
On a speedtime graph what do the following represent?
1. A line going upwards to the right.
2. A line going down to the right
3. A horizontal line
Feb 71:35 PM
Another Sketch A a parked car speeds up at a green light, reaching a constant speed of 50 km/h over a 30 second period. After 5 minutes of traveling at this speed, the car approaches a red light and slows to a stop over the course of 5 seconds. Sketch a possible speed versus time graph to represent the path of the car.
Feb 71:33 PM Feb 72:11 PM
The following containers are filled with water at a constant rate. For each container, sketch a graph to represent the height of the water over time.
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Smart Board Notes Unit 4.notebook
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January 26, 2016
Jan 312:53 PM
Some things to note when describing and sketching graphs:
1. Does the line pass through the origin
2. What is the scale of the y and xaxes?
3. What do these axes represent?
4. Where does the data start and end?
5. Is the data continuous or discrete?
Jan 312:36 PM
Problem set 3
p.28183. 3, 7, 11, 13, 18.
REMINDER: Do not forget about the other problem sets (1 and 2) or the worksheet (4.2) from last class.
Jan 312:28 PM
Discrete Vs Continuous Data
Jan 313:54 PM
Discrete data involves distinct, countable elements.
Jan 313:55 PM
Continuous data can take on any real value (within a given range)
Jan 312:08 PM
Expressing Domain and Range.
Recall:
The domain is the set of all possible values for the independent variable in a relation.
The range is the set of all possible values for the dependent variable given the domain.
Domain and range may be represented using
1. Words
2. A list
3. A real number line
4. Interval notation
5. Set notation.
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January 26, 2016
Jan 312:08 PM
Consider the following graph
What is the domain and range in words, as a list and on a number line?
Jan 313:13 PM
Consider the following graph.
What is the domain and range in words and on a number line?
Why not use a list?
Is this a function?
Jan 312:08 PM
Interval notation.
Symbols are used to indicate an interval of the set of real numbers.
This notation uses:
[ if the end number is included
( if the end number is not included
U When more than one interval is needed
∞ if there is no end pointNote: Discrete data should not be represented using interval notation.
Jan 318:11 PM
Use interval notation to express the domain and range.
Jan 312:33 PM
Set notation.
The formal and standard way to represent sets.
Set notation generally looks like
{ x | x < 3, x ∈ A }
"The set of""all x"
"such that" "is an element of"
Note:
1. the statement x < 3 may be any statement.
2. "A" many be any set such as W, N, I, Q, or R.
Jan 318:11 PM
Use set notation to express the domain and range.
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Smart Board Notes Unit 4.notebook
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January 26, 2016
Jan 312:34 PM
Some more examplesNumber line Interval Set
Notation Notation
Feb 27:38 PM
4.4 Linear Relations
Feb 27:47 PM
Linear relationships are relations of direct proportionality, or of constant change.
In other words, a relation is called linear if any change in an independent variable results in a corresponding (or constant) change in the dependent variable.
When plotted on a graph, a linear relation traces a straight line, hence the name.
Feb 28:02 PM
Ex 1. Which of the following graphs are linear?
Note: For linear relations, a constant change can be observed in both the independent and the dependent variable.
Feb 28:08 PM
Ex 2. Which of the following tables of values represent linear relations?
x f(x)
2 154 306 458 6010 75
x p(x)
1 12 43 94 165 25
x g(x)
6 53 50 53 56 5
Feb 28:43 PM
Ex 2. Which of the following sets of ordered pairs represent linear relations?
a) {(1, 2), (1, 1), (1, 0), (1, 1), (1, 2)}
b) {(0, 3), (1, 6), (2, 9), (3, 12), (4, 15)}
c) {(2, 8), (1, 1), (0, 0), (1, 1), (2, 8)}
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January 26, 2016
Feb 28:08 PM
Exploration:
For each of the following functions:
i) Generate a list of ordered pairs or a table[HINT: start with the input values 2, 1, 0, 1, and 2, then extend your graph if necessary].
ii) Graph the function and determine whether the relation is linear
1. f(x) = 2x + 3
2. g(t) = t2 t 1
Feb 29:07 PM
1. f(x) = 2x + 3
Feb 29:07 PM
1. g(t) = t2 + t 1
Feb 29:28 PM
In Sum, we can determine if a relation is linear by
1. Checking if the graph traces a straight line
2. Determining if a constant change in the independent variable results in a constant change in the dependent variable.
3. Observing the degree of the equation (linear relations are of degree 1).
Problem set 4.
Pg. 308. 3, 4, 5, 6 (i, iii, v).
Feb 46:41 PM
4.5 Characteristics of Linear Relations
Feb 47:02 PM
In this last section we will examine the following characteristics of linear relations:
1. Rate of change
2. Intercepts
3. Domain
4. Range
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January 26, 2016
Feb 36:35 PM
The Rate of Change of a Linear Relation is constant and can be determined by observing changes in the independent and dependent variable.
Consider the following relation:
The cost of a taxi is $3.50, plus $.75 for every km traveled.
Distance (km) Cost ($)
0 3.501 4.252 5.003 5.754 6.50
Feb 47:27 PM
As a graph:
Cost ($)
Distance (km)
Feb 47:54 PM
Example: The cost for a car rental is $60, plus $20 for every 100 km driven. What is the rate of change in the cost per kilometer?
Feb 47:37 PM
Some notes about rate of change.1. The steeper the line, the greater of the rate of change.
2. The sign of a rate of change (whether it is positive or negative), determines the direction of the line.
Side Question: What is the rate of change for each of the given graphs?
Feb 36:36 PM
Intercepts of a linear relation.
A horizontal (or x) intercept is a point where a line crosses the xaxis.
at these points y = 0, so, any xintercept can be represented as an ordered pair
A vertical (or y) intercept is a point where a line crosses the yaxis.
at these points x = 0, so, any yintercept can be represented as an ordered pair
Feb 49:11 PM
Examples. What are the x and yintercets for each of the following relations?
x x
x x
y y
yy
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January 26, 2016
Feb 55:49 PM
Finding x and yintercepts, given a linear relation.
To find a yintercept, let x = 0 and solve for y [i.e., solve f(0)].
To find the xintercept, let y = 0 and solve for x [i.e., let f(x) = 0].
Ex: Find the x and yintercepts for y = 2x + 3.
Feb 49:21 PM
Challenge Time! Sketch a linear relation with
Exactly 2 intercepts Exactly 1 intercept
An infinite number of intercepts
Feb 49:29 PM
Intercepts can have important meanings in contextual problems.
Note: Vertical intercepts often correspond to starting points and horizontal intercepts often correspond to ending points.
Feb 49:27 PM
State the Domain and Range for each Linear Relation.
x
y
x
y
x
y
x
y
Feb 36:43 PM
Contextual problems
This graph shows Mitchell leaving home at point A and going to a party at point F.
What was the slowest speed? What about the max?
Which point represents when he turned around to go back home. What might be a reason for this?
When did Mitchell stop? Why?
Feb 512:17 PM
Two Minute Write: Write a scenario for the following graph
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January 26, 2016
Feb 512:22 PM
Dominoe's Pizza charges $11.99 for a 12'' Hand Tossed pizza (this includes only cheese and pizza sauce). The cost per extra topping is $1.50.
Write an equation in two variables to represent the relation between the number of extra toppings and the cost of a pizza.
Graph the relation, assuming that you may have a maximum of 10 extra toppings.
Feb 55:54 PM
What is the rate of change? What does it represent?
What is the vertical intercept? What does it represent?
Is there an xintercept? explain.
What is the Domain and Range for the relation?
Feb 410:08 PM
We may sketch a graph of a linear relation if you know only two points (say, the x and yintercept).
Example: Sketch g(x) = 4x + 12.
Note: Be careful to determine if your data is continuous or discrete. If no context is provided, assume that it is continuous.
Feb 56:37 PM
If we only know the rate of change and a single point, we can also sketch a graph for a linear relation.
Ex: A large hot tub contains about 1500 liters of water and is being drained at a constant rate of 100 liters per minute. Sketch a graph that represents the amount of water in the hot tub as a function of time.
Feb 410:01 PM
Problem set 5.
Page 30809. 7, 14
Page 31922. 4, 5, 8, 16, 17
Jan 2611:35 AM