Math 10 Common

Unit 3 Relations and Functions

General Outcome: Develop algebraic and graphical reasoning through the study of relations.

In this unit, you will solve problems involving ...

Chapter 6 Linear Relations and Functions

Big Ideas

When you have completed this chapter, you will be able to...

Specific Outcome: It is expected that students will:

1. Interpret and explain the relationships among data, graphs and situations.

[C, CN, R, T, V] [ICT: C6 - 4.3, C7 - 4.2]

Open Specific Outcome 3.1 General Notes

General Notes

It is important that teachers view the nine specific outcomes in this topic as a package and not as individual outcomes. Teachers may choose to develop lessons and activities that include parts of several outcomes.

Prior knowledge from previous grade levels includes:

  • an introduction to linear relations, including tables of values and graphs (Grade 7)
  • graphing and analyzing two-variable linear relations (Grade 8)
  • using linear relations to solve problems, including graphing, interpolation and extrapolation (Grade 9).

Technology [T] has been identified as one of the mathematical processes to be emphasized in completing this outcome. It is expected, however, that students will be able to graph both linear and nonlinear data with and without the use of technology.

Students are expected to draw graphs that include a title, properly label led axes and appropriate scales.

For a given context, students are expected to identify key points on a graph, such as intercepts or points where the graph changes direction.

While students may have previously discussed restrictions on the variables in a linear relation, this is the first time that the terms domain and range are addressed. Some ways students may describe the domain and range for a linear relation include:

  • written or verbal descriptions
  • lists
  • set builder notation; e.g. ,{ x |–2  ≥  x < 3, x ∈  R }

  • interval notation; e.g., (–2, 3).

It is essential that students understand and are able to use set builder notation and interval notation effectively since these will be the primary ways of describing sets of numbers in future courses including Mathematics 20-1 and 20-2.

Students are expected to distinguish between continuous and discrete data and understand their implications for a graph.

Open Achievement Indicators

Achievement Indicators

Acceptable Standard

Standard of Excellence

3.1.1 Graph, with or without technology, a set of data, and determine the restrictions on the domain and range. **
3.1.2 Explain why data points should or should not be connected on the graph for a situation. **
3.1.3 Describe a possible situation for a given graph. **
3.1.4 Sketch a possible graph for a given situation. **
3.1.5 Determine, and express in a variety of ways, the domain and range of a graph, a set of ordered pairs or a table of values. Use written or verbal descriptions and lists. State domain and range correctly in set builder or interval notation.

Specific Outcome: It is expected that students will:

2. Demonstrate an understanding of relations and functions.

[C, R, V]

Open Specific Outcome 3.2 General Notes

General Notes

This is the first time the concept of a function is introduced in the Kindergarten to Grade 12 Mathematics curriculum. Students are expected to develop a good understanding of the concept at this level as the study of functions is a recurring topic in grades 11 and 12.

Students are expected to discover, through investigation, the rules for distinguishing between relations and functions.

Students are expected to identify functions expressed in multiple formats; e.g., graphs, tables of values, lists of ordered pairs and mapping diagrams.

Open Achievement Indicators

Achievement Indicators

Acceptable Standard

Standard of Excellence

3.2.1 Explain, using examples, why some relations are not functions but all functions are relations. **
3.2.2 Determine if a set of ordered pairs represents a function. **
3.2.3 Sort a set of graphs as functions or non-functions. **
3.2.4 Generalize and explain rules for determining whether graphs and sets of ordered pairs represent functions. Determine without explanation. Determine with explanation.

Specific Outcome: It is expected that students will:

4. Describe and represent linear relations, using:

[C, CN, R, V]

Open Specific Outcome 3.4 General Notes

General Notes

Students are expected to investigate relations represented in a variety of ways and explain why a given relation is or is not a linear relation.

With the exception of Achievement Indicator 4.3, in determining whether a given relation is or is not a linear relation, the explanation should be more detailed than stating whether or not the graph is a straight line. For example, if the relation is given as a set of ordered pairs or a table of values (Achievement Indicator 4.4), the explanation should make reference to the constant rate of change (slope) between any two points.

Students may be familiar with some of the vocabulary used in representing relations and functions; the terms input and output values are sometimes used in previous grade levels. In science courses, students may encounter the terms manipulated and responding variables; however, students are expected to use the formal terminology generally used in mathematics courses; i.e., independent variable and dependent variable.

In Achievement Indicator 4.6, students are expected to investigate different equations and develop a rule for determining which equations represent linear relations.

In Achievement Indicator 4.7, students are expected to recognize different representations of the same linear relation; i.e., students are expected to select from a list those representations (words, ordered pairs, tables of values, graphs, equations) that represent the same linear relation.

Open Achievement Indicators

Achievement Indicators

Acceptable Standard

Standard of Excellence

3.4.1 Identify independent and dependent variables in a given context. **
3.4.2 Determine whether a situation represents a linear relations, and explain why or why not. **
3.4.3 Determine whether a graph represents a linear relation, and explain why or why not. **
3.4.4 Determine whether a table of values or a set of ordered pairs represents a linear relation, and explain why or why not. **
3.4.5 Draw a graph from a set of ordered pairs within a given situation, and determine whether the relationship between the variables is linear. **
3.4.6 Determine whether an equation represents a linear relation, and explain why or why not. **
3.4.7 Match corresponding representations of linear relations. **

Specific Outcome: It is expected that students will:

5. Determine the characteristics of the graphs of linear relations, including the:

[CN, PS, R, V]

Open Specific Outcome 3.5 General Notes

General Notes

Slope, domain and range are introduced in other outcomes. In this outcome, students are expected to relate, through investigation, these characteristics to the graphs of linear relations.

Students are expected to indicate the significance of intercepts, slope, domain and range, within the context of a problem.

Students are expected to state any restrictions on the domain and range of a linear relation, within the context of a problem.

In Achievement Indicator 5.4, students are expected to determine, through investigation, how they would draw a line that has one, two or an infinite number of intercepts.

Open Achievement Indicators

Achievement Indicators

Acceptable Standard

Standard of Excellence

3.5.1 Determine the intercepts of the graph of a linear relation, and state the intercepts as values or ordered pairs. **
3.5.2 Determine the slope of the graph of a linear relation. **
3.5.3 Determine the domain and range of the graph of a linear relation. Use written or verbal descriptions, including tables or lists. State domain and range correctly in set builder or intercept notation
3.5.4 Sketch a linear relation that has one intercept, two intercepts or an infinite number of intercepts. **
3.5.5 Identify that graph that corresponds to a given slope and y-intercept. **
3.5.6 Identify the slope and y-intercept that correspond to a given graph. **
3.5.7 Solve a contextual problem that involves intercepts, slope, domain or range of a linear relation. Solve simple contextual problems. Solve complex contextual problems.

Specific Outcome: It is expected that students will:

8. Represent a linear function, using function notation.

[CN, ME, V]

Open Specific Outcome 3.8 General Notes

General Notes

It is important that students understand the meaning of the symbols used in function notation. Function notation will be used extensively to represent functions in grades 11 and 12.

In using function notation, students are expected to choose variables that are meaningful in the context being described; e.g., if a linear relation describes the height of an object as a function of time, then the variables selected should reflect these quantities, as in h(t) = 5t+ 20.

A function of an algebraic expression, such as f(2x–3), is not part of this outcome.

Students are expected to connect function notation to other representations of linear relations; i.e., words, ordered pairs, tables of values, graphs.

Open Achievement Indicators

Achievement Indicators

Acceptable Standard

Standard of Excellence

3.8.1 Express the equation of a linear function in two variables, using function notation. **
3.8.2 Express an equation given in function notation as a linear function in two variables. **
3.8.3 Determine the related range value, given a domain value for a linear function; e.g., if f(x)=3x-2, determine f(-1). **
3.8.4 Determine the related domain value, given a range value for a linear function; e.g., if g(t) = 7+t, determine t so that g(t) = 15. **
3.8.5 Sketch the graph of a linear function expressed in function notation. **

.

6.1 Graphs of Relations

Focus on...

Purposes of a graph:

X- axis (horizontal)
Manipulated or independent variable.
One you change on purpose or manipulate.

Y-axis (vertical)
Responding or dependent variable.
One you measure as a result of the changes.

Line patterns
Horizontal lines are used if one quantity is not changing relative to a change in the other quantity.
NEED DIAGRAM

When comparing two quantities, straight lines are used to indicate a constant change in the relationship.
Proportional straight line up to the right through (0,0)
NEED DIAGRAM

Positive linear relationship, a straight line that goes up to the right not through (0,0).
When X increases than Y increases.
NEED DIAGRAM

Negative linear relationship, a straight line that goes down to the right.
When X increases, Y decreases.
NEED DIAGRAM

Curves are used when the rate of change is not constant. Used in math 20.

.

6.2 Linear Relations

Focus on...

Relation

An association between two quantities.
Can be presented in words, as an equation, as ordered pairs, as a table of values, or as a graph.

Linear relation

A relation that forms a straight line when the data are plotted on a graph.

Non-linear relation

A relation that does not form a straight line when the data are plotted on a graph.

Discrete data
Data values on a graph that are not connected. Fractions and decimals don't make sense
Example: A pasta supper costs $8 per person. It is not possible to have 4.5 people.
NEED DIAGRAM

Continuous data
Data values on a graph that are connected. Fractions and decimals do make sense.
Example: a tool rental store charges $2 per hour. Renting a tool for 1.5 hours makes sense.
NEED DIAGRAM

Independent variable
The variable for which values are selected or changed. Always on the X (horizontal) axis.

Dependent variable
The variable whose values depend on those of the independent variable. Always on the Y (vertical) axis.
NEED DIAGRAM

.

6.3 Domain and Range

Focus on...

Domain

The set of all possible values for the independent variable in a relation.

The domain for a relation is the set of all numbers for which the independent variable is defined.
The domain of a relation may also be described as:

Range

The set of all possible values for the dependent variable as the independent variable takes on all possible values of the domain.

The range of a relation is the set of all numbers for which the dependent variable is defined.
The range of a relation may also be described as:

Set Notation
{x ∈ | -2 ≤ x ≤ 10}
NEED NUMBER LINE DIAGRAMS

.

6.4 Functions

Focus on...

Function

A relation in which each value of the independent variable is associated with exactly one value of the dependent variable
For every value in the domain there is a unique value in the range.

Each function has its own formula, or rule, that is often given using a special notation, called function notation.
All functions are relations but not all relations are functions.

Function notation

A symbolic notation used for writing a function
f(x) is read as "f of x" or "f at x"

Vertical line test

A test to see if a graph represents a function.
If any vertical line intersects the graph at more than one point, the relation is not a function.








.

6.5 Slope

Focus on...

Slope

The ratio of the vertical change, or rise (Y axis), to the horizontal change, or run (X axis) of a line or line segment.
Slope can have units, Y axis per X axis.

The slope of a line is the ratio of the rise to the run.
slope = rise / run
The slope of a line can be determined using two points on a line, (x1, y1) and (x2, y2).
If you know one point on the line you can use the slope to find other points on the line.
The slope is the average rate of change.