Name ______Class ______Date ______
Practice 5-2Properties of Parabolas
If a > 0, find the minimum value. If a < 0, find the maximum value.
1.y = –x2 + 2x + 3 2. y = 2x2 + 4x – 3
3. Suppose you are tossing an apple up to a friend on a third-story balcony. After t seconds, the height of the apple in feet is given by h = –16t2 + 38.4t + 0.96.Your friend catches the apple just as it reaches its highest point. How long does the apple take to reach your friend, and at what height above the ground does your friend catch it?
4. The barber’s profit p each week depends on his charge c per haircut. It is modeled by the equation . What price should he charge for the largest profit?
5. A skating rink manager finds that revenue R based on an hourly fee F for skating is represented by the function R = – 480F2 + 3120F. What hourly fee will produce maximum revenues?
6. The path of a baseball after it has been hit is modeled by the function h = – 0.0032d2 + d + 3, where h is the height in feet of the baseball and d is the distance in feet the baseball is from home plate. What is the maximum height reached by the baseball? How far is the baseball from home plate when it reaches its maximum height?
7. A lighting fixture manufacturer has daily production costs of C = 0.25n2 – 10n + 800, where C is the total daily cost in dollars and n is the number of light fixtures produced. How many fixtures should be produced to yield a minimum cost?
8. A model for a company’s revenue is R = -15p2 + 300p + 12,000, where p is the price in dollars of the company’s product. What price will maximize revenue? Find the maximum revenue.
9. The equation for the motion of a projectile fired straight up at an initial velocity of 64 ft/s is
h = 64t – 16t2, where h is the height in feet and t is the time in seconds. Find the time the projectile needs to reach its highest point. How high will it go?
10. The equation for the cost in dollars of producing automobile tires is C = .000015x2 – 0.03x + 35, where x is the number of tires produced. Find the number of tires that minimizes the cost. What is the cost for that number of tires?
11. A rock club’s profit from booking local bands depends on the ticket price. Using past receipts, the owners find that the profit p can be modeled by the function p = -15t2 + 600t + 50, where t represents the ticket price in dollars. Find the price that yields the maximum profit. What is the maximum profit?
12. A town is planning a playground. It wants to fence in a rectangular space using an existing wall. What is the greatest area it can fence in using 100 ft of donated fencing?