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Functions. Section 8.1. Notes: Relations and Functions. The ________________ is a value that does not depend upon another variable. The _________________ is a value that depends on the input value.
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Functions Section 8.1
Notes: Relations and Functions • The ________________ is a value that does not depend upon another variable. • The _________________ is a value that depends on the input value. • Recall that functions are _________ in which each element of the domain is paired with __________ one element of the range.
Examples • Determine whether each relation is a function. Explain. • 1. (5,1), (6,3), (7,5), (8,0) • 2. (54,112), (56,130), (55,145), (54,123), (56,128)
Notes: Relations and Functions • Another way to determine whether a relation is a function is to apply the ___________ to the graph of the function. • If, for each value of x in the domain, a vertical line passes through no more than one point on the graph, then the graph represents a function. • If the line passes through more than one point on the graph, it is not a function.
Example • 3. Determine whether the graph is a function. Explain your answer.
Notes: Function Notation • A function that is written as an equation can also be written in a form called ____________. • Consider the equation y = 2x + 3
Notes: Function Notation • The variable y and f(x) both represent the _________ variable. • In the example above, when x = ____, f(x) = ____ • In function notation, f(x) is read “f of x” and is equal to the value of the function at x.
Examples • If f(x) = 14 + 3x, find each function value: • 1. f(4)= • 2. f(-7)=
Notes: Describe Relationships • A function can also describe the relationship between two quantities. • For example, the distant you travel in a car depends on how long you are in he car. • In other words, distance is a function of time or d(t)
Example • 1. A whale watching boat traveled at a sped of 5.5 miles per hour. • A. Identify the independent and dependent variables. Then write a function to represent the total distance traveled in any number of hours spent whale watching. • B. Use the function to find how long it took to travel 25 miles. Round to the nearest tenth.
Practice • Determine whether each relation is a function.
H.O.T. Problems • 38. Draw two graphs, one that represents a relation that is a function and one that represents a relation that is not a function. Explain why each graph is or is not a function.
H.O.T. Problems • 46. How can the relationship between water depth and time to ascend to the water’s surface be a function? • Explain how the two variables are related. Discuss whether water depth can ever correspond to two different times.