Functions and Writing Functions

Find the function rule.

• y = 2x

• y = 2x+3

• y = 3x+3

• y = -2x+3

Find the function rule.

• y = -2x +10
• y = -2x -10
• y = 2x +10
• y = 2x-10

A pizzeria charges $12 per pizza plus an additional $3 for delivery. Which equation represents the cost of having any number of pizzas delivered?

• c = 12p + 3
• c = 12p
• c = 3p
• c = 12 + 3p

Identify the function rule that best represents the following statement:
A bottle rocket is being launched from the roof of an 80 meter tall building. If the rocket travels straight up at a rate of 22 m/s, what is the total height of the rocket as a function of time?

• H = 108x
• H = 80 - 22x
• H = 80 + 22x
• H = 80x + 22

Identify the function rule that best represents the following statement:
A soda machine sells drinks for 75 cents each. Let d represent the number of drinks bought and C represent the total cost.

• d = $0.75C
• d = $0.75 + C
• C = $0.75 + d
• C = $0.75d

A plumber charges a service fee of $40 plus $25 per hour for labor.
(A) Write a function rule for the total cost of hiring the plumber for a job that takes x hours.
(B) How much would it cost to hire the plumber for a job that takes 4 hours?

• (A) y = 40 + 25x
  (B) $140
• (A) y = 40x + 25
  (B) $185
• (A) y = 40 + 25x 
  (B) $185
• (A) y = 40x + 25 
  (B) $140

The school cafeteria has 285 cartons of milk in stock. Each day, a total of 60 cartons are sold. Which function rule best represents this situation?

• y = 285x + 60 
• y = 285x - 60
• y = 285 - 60x
• y = 285 + 60x

A water tank holds 84 gallons. When it began to leak it lost 3 gallons every hour. Write an equation to find the amount of water "y" the tank will have after "x" number of hours.

• y = 84 - 3x
• y = 3 - 84x

Identify the function rule that best represents the following statement:
The total cost (C) for kilograms of beef (k) if each kilogram costs ​$2.55

• C = 2.55k
• C = 2.55 + k
• C = 2.55 - k
• C = 2.55k + 2.55

Identify the function rule that best represents the following statement:
An apple rolled off a 4 ft table and fell at an average velocity of 0.8 ft/sec. Let h represent the height off the ground of the apple and t the falling time. 

• h = 4 - 0.8t
• h = 4 + 0.8t
• h = 4.8t
• h = 3.2t