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| 11 Theory slides |
| 10 Exercises - Grade E - A |
| Each lesson is meant to take 1-2 classroom sessions |
Here are a few recommended readings before getting started with this lesson.
Tadeo, the younger brother of Vincenzo, loves watching Vincenzo's college basketball games. He recorded Vincenzo and his teammates' names, heights, and the number of 3-point shots they made. Tadeo describes the relation between Vincenzo's teammates' height and the number of 3-points shots they made. He is so excited to share them with his big sibling.
A relation, or relationship, is a rule that relates the elements of one set to the elements of another set. The first set is called the set of inputs and the second set is called the set of outputs.
A mapping diagram is a graphic tool that helps to visualize a relation. In a mapping diagram, the inputs are listed in one set and the outputs in another. Then, arrows are drawn from each input to its corresponding outputs.
Tadeo enjoyed sharing his last finding so much that he now wants to examine the relationship between the height and age of Vincenzo's teammates. He wants to describe some relations based on the values in the following diagram.
Table of Values:
Ages | 16 | 18 | 21 | 22 | 21 |
---|---|---|---|---|---|
Heights (m) | 1.70 | 1.75 | 1.85 | 1.96 | 1.91 |
Mapping Diagram:
Ordered Pairs: {(16,1.70), (18,1.75), (21,1.85), (22,1.96), (21,1.91)}
Coordinate Plane:
To make a mapping diagram, place all the ages in one set and all the heights in another set. Then, connect each age with its corresponding height using an arrow. To write the relation as a set of ordered pairs, place the ages in the first component and the corresponding heights in the second component.
Using the information that Tadeo gathered, a relation between the ages and heights can be made and represented using different visualizations.
First, organize the relation using a table of values. Place the ages in the first row and the heights in the second row. Align the ages with the corresponding heights.
Ages | 16 | 18 | 21 | 22 | 21 |
---|---|---|---|---|---|
Heights (m) | 1.70 | 1.75 | 1.85 | 1.96 | 1.91 |
Relation | Inputs | Domain |
---|---|---|
{(0,-2),(1,0),(2,2)} | 0, 1, 2 | {0,1,2} |
Relation | Outputs | Range |
---|---|---|
{(0,-2),(1,0),(2,2)} | -2, 0, 2 | {-2,0,2} |
The following applet displays a relation either as a table, a set of ordered pairs, a mapping diagram, or a group of coordinate points in the coordinate plane. For any given relation, determine its domain and range.
The following applet displays two relations. Determine if they represent the same relation.
Consider all of the diagrams given at the beginning of the lesson. Compare the information that each diagram provides and see if they correspond to each other.
The first diagram shows a relation represented as a table. It consists of rows and columns, where each row represents an ordered pair. The first column represents the input values (x-values), and the second column represents the output values (y-values).
To compare with other representations, ensure that the values in the table match the input-output pairs provided in other diagrams.
The second diagram visually represents a relation by using arrows to connect the input values with their corresponding output values. The input values are shown on the left side, and the output values on the right side.
Notice that the arrows in the mapping diagram correctly link the input values to their respective output values. This is the same as the pairs shown in the table.
Finally, the fourth diagram shows a relation as a group of coordinate points in the coordinate plane. Recall that each point consists of an x-coordinate and a y-coordinate.
Consider a relation represented by the following mapping diagram.
The table shows the relationship between x- and y-values.
Input, x | 5 | -5 | 3 | -4 | 4 |
---|---|---|---|---|---|
Output, y | -5 | 5 | -3 | 4 | -4 |
Which graph represents the same relation?
A mapping diagram illustrates how each element in the input is paired with an element in the output. An ordered pair is a set of numbers written in the form (x,y), where x is a number from the input and y is a number from the output.
Looking at where the arrows start and end, we can state the x-coordinates and their corresponding y-coordinates of the ordered pairs. We get the ordered pairs by pairing these values. ( 1, 1), ( 2, 4), ( 3, 9), ( 4, 16),( 5, 25) Since a relation can also be thought of as a set of ordered pairs, we write these ordered pairs between curly braces. { ( 1, 1), ( 2, 4), ( 3, 9), ( 4, 16),( 5, 25) } This set matches the set in Option A.
In the given table, the first row represents the input values (x-values), and the second row represents the output values (y-values).
Input, x | 5 | - 5 | 3 | - 4 | 4 |
---|---|---|---|---|---|
Output, y | - 5 | 5 | - 3 | 4 | - 4 |
An ordered pair is a set of numbers written in the form (x,y), where x is a number from the input and y is a number from the output. Looking at each column, we can state the x-coordinates and their corresponding y-coordinates. We get the ordered pairs by pairing these values. ( 5, - 5), ( - 5, 5), ( 3, - 3), ( - 4, 4),( 4, - 4) Let's plot these points on a coordinate plane. We will place the inputs along the horizontal axis and the outputs along the vertical axis.
This graph matches the graph in Option C.
We are given a set of ordered pairs representing the number of people in a park. { (1,26),(2,30),(3,30),(4,36),(5,38) } To express the set of given ( x, y) ordered pairs as a mapping diagram, we will list all of the unique x-values in one vertical list and all unique y-values in another vertical list. Then, we can use arrows to connect corresponding x- and y-values.
Notice that one element in the range have mapped more than one element in the domain. We did not write the same element, 30, in the range twice, instead we drew two arrows pointing to that element. Among the given options, the diagram in Option B matches the diagram we drew.
The graph represents the number of teams in each round of a football tournament.
We are given a graph that shows the number of teams in each round of a football tournament. To determine the domain of the relation, we will identify the x-coordinates of the points. We will trace along the grid lines from each point to the x-axis.
The domain of this relation is the set of all unique x-values, which are 1, 2, 3, and 4. Domain: {1,2,3,4 }
The y-coordinates of the points will be the elements of the range of the relation. Let's identify the y-coordinates of the points.
The y-coordinates are 4, 8, 16, and 32. Therefore, the range of the relation consists of those numbers. Range: {4,8,16,32 }
The following table shows the amount of garbage that was produced in England each year between 2017 and 2022.
Year, t | 2017 | 2018 | 2019 | 2020 | 2021 | 2022 |
---|---|---|---|---|---|---|
Garbage, G (million tons) | 23.6 | 23 | 23 | 23 | 23.8 | 23.7 |
The table represents a relation which assigns an input t to the total amount of garbage G produced in that year.
We want to express the domain of a relation represented as a table. In the table, the input values are represented by t, a year between 2017 and 2022. This means that the domain consists of those values.
We see that the domain is the set of all unique t-values. Domain {2017,2018,2019,2020,2021,2022 }
From the table, we see that each element in the first row is paired with an element in the second row. Those values will form the range of our relation.
We see that one of the values appears three times in the second row. We include it only once when forming the set of range. Let's form the set by listing the numbers from least to greatest, and including each element only once. Range {23,23.6,23.7,23.8 }