Use the vertical line test to determine if each relation is a function. (See Objective 3.) 79. 80. –4 x 81. 82. 6 Find the requested information. (See Objective 4.) 83. f (-3) if f (x) = -2x2 + x + 3 84. The function f (x) is given by Y1. Find a. f (-2) and b. x if f (x) = -14. 2 4 –2 y 2 2 4 4 –2 –4 –4 x y 2 2 4 4 6 –2 –2 –4 x y 2 2 4 4 –2 –4 –2 –4 x y 85. The graph of f (x) is given below. Find a. f (0) and b. x if f (x) = 4. –4 –2 2 x 6 4 4 –2 y 86. Find f (1.5) if f (x) = 3.4x - 0.5. Write each linear equation in two variables in function notation. Then find f (0), f (3), and f (-2) and write the corresponding ordered pairs. (See Objective 5.) 87. 2x - 7y = 21 88. y = u4x + 1u Solve each problem. (See Objective 5.) 89. Rikki has a new job as a math instructor at a local community college. Her starting salary is $43,200 with a regular annual teaching load of 30 credit hours. If she teaches beyond the regular load, she earns $1020 per credit hour. a. Write a linear function f (x) that represents Rikki’s yearly income, where x is the number of extra credit hours Rikki teaches. b. If Rikki teaches two 3-credit-hour courses in addition to her regular load, what is her income? c. Find f (9) and interpret the answer. 90. Wong purchases a new car for $16,400. The car’s value decreases by $1325 each year. a. Write a linear function that represents the value of the car, where x is the age of the car in years. b. What is the car’s value after 3 yr? c. Find f (5) and interpret the answer. CHAPTER 3 TEST / LINEAR EQUATIONS IN TWO VARIABLES 1. The point (2, -4) is a solution of the equation a. y = 2x + 8 b. x = -4 c. 2x - y = 8 d. y = ux - 6u 2. If a > 0 and b < 0, then the point (a, b) lies in a. Quadrant I b. Quadrant II c. Quadrant III d. Quadrant IV Graph each equation by creating a table of solutions. 3. y = x2 + 1 4. y = ux + 2u 5. Is the point (-1, 1) a solution of the equation shown in the graph? 2 2 4 4 –2 –4 –2 –4 x y 6. The average price (rounded to the nearest dollar) of brand name prescription drugs for certain years is shown in the table. Year 1995 2000 2005 2006 2007 Average price of brand name drugs 40 65 98 107 120 a. Write an ordered pair for each year, where x is the number of years after 1995 and y is the average price. b. Interpret the meaning of the first and last ordered pairs. c. Plot the ordered pairs to form a scatter plot of the given data. 286 Chapter 3 Linear Equations in Two Variables
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