Algebra 1
5.4 ‐ Writing a Function Rule
A. Writing a function rule from a table
• If you are given a table of x and y values, we can determine how y relates to x and then write a function rule, or an equation to represent those coordinates
• In order to determine the function rule, ask yourself, “What can I do to the x value to get the y value?”
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B. Examples. Write the function rule for the following tables.
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C. Write a function rule for each situation
4. The total cost t(c) of ounces of coffee if each ounce costs $.34.
5. The total distance f(d) in feet between two houses in your neighborhood, if you know the distance in yards.
6. The amount you have to tip your waiter or waitress, f(t) based upon the cost of your meal. (A fair tip is between 15% and 20% of your bill)
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D. Applications. Solve the following real world application problems
7. The journalism class makes $25 per page of advertising in the yearbook. If the class sells p pages of advertising, how much money will it earn?
(a) Write a function rule to describe this relationship.
(b) The class sold six pages of advertising. How much did the class make?
8. The choir spent $100 producing audio tapes of its last performance and will sell the tapes for $5.50 each. Write a rule to describe the choirs profit as a function of the number of tapes sold, t. Jan 15­6:54 AM
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5.4 HW p. 272 #s 1 ­ 20, 24, 31, 32
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