How Can You Determine When the Relationship Between Two Quantities Is a Function?

Explain how you know whether a relationship between two quantities is or is not a function. Choose a pair of input-output from the table as an example, if that would be helpful.

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8.F.A.1

Decide if the relationship between each pair of input and output can be seen as a function.

input	output	a function?
month of the year	number of days in the month
number of days in a month	month of the year
weight in kilograms	weight in pounds
weight in pounds	weight in kilograms
student's age	student's shoe size
your height in inches	your age

• yes

• no

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8.F.A.1

The graph shows the temperature between noon and midnight one day in a certain city. What was the temperature at 9 p.m.? When was the temperature increasing? When was the temperature 55 degrees? Is temperature a function of time? Explain your reasoning. Is time a function of temperature? Explain your reasoning.

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8.F.B.5

What is the definition of a function?

• Has inputs and outputs

• Inputs have different outputs every time

• Every input has exactly one output

• There are x-values and y-values

Determine if the graph is a function. `​​ (a)   `

• Function

• Not a Function

Determine if the graph is a function. `​ (a)   `

• Not a Function

• Function

Determine if the graph is a function. `​​ (a)   `

• Function

• Not a Function

Does the mapping of these points represent a function? (Note: the left oval represents your x values and the right oval represents your y values)

• Function

• Not a Function

Determine if the graph is a function. `​ (a)   `

• Not a Function

• Function

When the ordered pair (2,2) is added to the table, the table ​ (a)   represent y as a function of x because each value of x ​ ​ (b)   correspond to a unique value of y.

• will not

• will