options: Functions: students learn to define, use, and evaluate functions to model relationships between quantities.

Number & Operations - Fractions: students learn to understand fractions as numbers and may work with them using addition, subtraction, multiplication, and division.

Counting & Cardinality: students learn to know number names and the count sequence, count to tell the number of objects, and compare numbers.

Modeling: students learn to choose and use appropriate mathematics and statistics to analyze real-world empirical situations, improve decisions, and report on their conclusions and the reasoning behind them.

Measurement & Data: students learn to work with data and measure attributes such as time, money, length, area, and volume. They may learn to compare measurements to operations and convert between different units of measure.

Operations & Algebra: students learn to solve problems using algebraic thinking and operations such as addition, subtraction, multiplication, and division. They may learn to identify and explain arithmetic patterns, evaluate or manipulate numerical expressions, and reason with equations and inequalities.

Geometry: students learn to classify geometric figures by their properties, and understand and compare the relationships between them. Students develop and use formulas to compute lengths, areas, and volumes, and they use transformations to generate new shapes and compare existing ones. Geometry can be studied with and without coordinates.

Statistics & Probability: students learn to analyze and produce data distributions, and build understanding of univariate and bivariate data. They learn to interpret data, make statistical inferences, justify conclusions, understand rules of probability, and use probability to make decisions.

Number & Operations in Base Ten: students learn to work with the base-ten system and build place value understanding.

Number Systems and Quantity: students learn to understand the complex number system and reason quantitatively.

Ratios & Proportional Relationships: students learn to recognize, describe, represent, and reason with ratios, rates, proportional relationships, and percent.
problem_activity: Optional activity
Previously, students made sense of the domain of functions in concrete contexts. This optional activity is an opportunity to reason about domain more abstractly. Students evaluate an expression that defines a function at some values of input and notice a value that produces an undefined output. They graph the function to examine its behavior, and then think about how to describe the domain of the function.
Launch
Provide access to graphing technology.
Action and Expression: Provide Access for Physical Action.
Provide access to tools and assistive technologies such as a graphing calculator or graphing software. Some students may benefit from a checklist or list of steps to be able to use the calculator or software.
Supports accessibility for: Organization; Conceptual processing; Attention
Student Facing
Consider the function
\(f(x)=\dfrac {6}{x-2}\)
.
To find out the sets of possible input and output values of the function, Clare created a table and evaluated
\(f\)
at some values of
\(x\)
. Along the way, she ran into some trouble.
Find
\(f(x)\)
for each
\(x\)
-value Clare listed. Describe what Clare’s trouble might be.
{"table": [{"_attributes": {"border": "1"}, "tbody": [{"tr": [{"th": [{"_attributes": {"scope": "row"}, "span": [{"_attributes": {"class": ["math", "math-repaired"], "data-png-file-id": "50"}, "_value": "\\(x\\)"}]}], "td": [{"_value": "-10"}, {"_value": "0"}, {"span": [{"_attributes": {"class": ["math", "math-repaired"], "data-png-file-id": "238"}, "_value": "\\(\\frac12\\)"}]}, {"_value": "2"}, {"_value": "8"}]}, {"th": [{"_attributes": {"scope": "row"}, "span": [{"_attributes": {"class": ["math", "math-repaired"], "data-png-file-id": "287"}, "_value": "\\(f(x)\\)"}]}], "td": [{}, {}, {}, {}, {}]}]}]}]}
Use graphing technology to graph function
\(f\)
. What do you notice about the graph?
Use a calculator to compute the value you and Clare had trouble computing. What do you notice about the computation?
How would you describe the domain of function
\(f\)
?
Student Response
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Student Facing
Are you ready for more?
Why do you think the graph of function
\(f\)
looks the way it does? Why are there two parts that split at
\(x=2\)
, with one curving down as it approaches
\(x=2\)
from the left and the other curving up as it approaches
\(x=2\)
from the right?
Evaluate function
\(f\)
at different
\(x\)
-values that approach 2 but are not exactly 2, such as 1.8, 1.9, 1.95, 1.999, 2.2, 2.1, 2.05, 2.001, and so on. What do you notice about the values of
\(f(x)\)
as the
\(x\)
-values get closer and closer to 2?
Student Response
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click here to register or sign in
for free access to Extension Student Response.
Activity Synthesis
Display a graph of the function for all to see. Invite students to share their observations of the behavior of function
\(f\)
based on the completed table and their graph. Solicit their ideas on what the problem might be with this function.
If no students mentioned division by 0 as the issue, bring this up. Ask questions such as:
"What happens when we divide a number by 0?" (The result is undefined.)
"In the expression
\(\dfrac {6}{x-2}\)
, what value or values of
\(x\)
would result in a denominator of 0?" (Only 2 gives a denominator of 0.)
"If 2 does not produce an output, is it a possible input for
\(f\)
?" (No)
Highlight that the domain of
\(f\)
includes all numbers except 2.


correct_option_index: 0

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