3.3 Inverse of the Quadratic Function
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Transcript of 3.3 Inverse of the Quadratic Function
Unit 3 – Quadratic Functions Date: 3.3 The Inverse of the Quadratic Function
Homework: Page 161-‐162 Questions #2, 3, 4, 6, 9, 11, 12, 16, 17 Learning Objectives/Success Criteria: At the end of this lesson I will be able to:
o Recall how to find an inverse of a quadratic function including the domain and range o Solve application problems related to the inverse function
Recall: To find the inverse of a quadratic, you must complete the square first. Given f (x) = −x2 + 20x − 99 , find f −1(x) . Recall: To graph the inverse of a parabola, you can find the inverse of the vertex and sketch the graph.
a) Given f (x) = x2 − 2x + 6 , sketch a graph of f −1(x) b) Is f −1(x) a function? What restrictions can you put on f −1(x) to make it a function?
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Example 1: At the traffic safety bureau, Matthew determines that for a car travelling at approximately 100km/h, the distance, in metres, it takes to stop once the brakes are applied is approximately given by d(t) = −2.8t2 + 28t , where t is the time, in seconds.
a) Determine the inverse of this function. What does this represent in the context of the question? b) In the context of this question, what should the domain and range of the original function and its
inverse be? Example 2: A small skateboard company is trying to determine the best price for its boards. When the boards are priced at $80, 120 are sold in a month. After doing some research, the company finds that each increase of $5 will result in selling 15 fewer boards.
a) Write an equation to represent the revenue, R, in dollars, as a function of x, the number of $5 increases. State the domain and range of the function.
b) What change in price will maximize revenue? c) Determine the inverse of the revenue function. What does this equation represent in the context of the
question? State the domain and range of the inverse. d) Determine the number of $5 increases for a revenue of $8100.