Function rules

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Function Rule:

Function Rule Algebra


Review A relation is a set of ordered pairs. A function is a relationship that assigns exactly one output value (range) for each input value (domain). For each input there is only one corresponding output. 3 ways to view a function: Function rule Function table Graph REMEMBER: x = input = domain = independent y = output = range = dependent = also called f (x) at times

Creating a function rule:

Creating a function rule Begin by analyzing the data you have – usually a table of values or series of points on a graph (which you can make into a table). Look for the pattern relating the x and y values. X Y 1 -1 2 0 3 1 4 2 Ask yourself, “What do I need to do to the x value, 1, to get the y value, -1? 2 to get 0? 3 to get 1? 4 to get 2?” You subtract 2 each time, therefore, y = x - 2

Creating a function rule:

Creating a function rule What is the relation between x and y? 1 x 1 = 1 2 x 2 = 4 3 x 3 = 9 4 x 4 = 16 SO… y = x * x y = x 2 X Y 1 1 2 4 3 9 4 16

Creating a function rule:

Creating a function rule Write a function rule to calculate the cost of buying apples at $0.48 per pound. The y (range) value is the dependent variable so it is what we need to find – total cost. The x (domain) value is the independent variable that we will use to determine cost – the number of pounds bought. y = $0.48 * the number of pounds of apples bought y = $0.48x How much would 8.7 lbs cost? x = 8.7 y = $0.48 (8.7) y = 4.176 round up to $4.18

Watch the videos linked below:

Watch the videos linked below Click on the links below to see further discussion: formula function Please copy the examples given in the videos into your notes


Practice Click on the link below to practice identifying parts of a function. functions_1

Further Reference:

Further Reference For more information or examples on this topic, please see: Textbook p. 7functionrulep.cfm functionmachine.html / Please write down any specific questions you have so we can discuss them in class!!