Interpreting a Function

The function d(x) where x=gallons of gas and d(x)= # of miles traveled.
Interpret d(8)=300 in context.

• A car with 8 gallons of gas can travel 300 miles.
• A car traveling 8 miles has 300 gallons of gas.
• A car is traveling 300 miles.
• The car traveling 8 mph can go 300 miles.

The function W(x) where x=inches of rain and W(x)= # of wildflowers growing.
Interpret W(5)=75

• With 75 inches of rain, there are 5 wildflowers growing.
• When it rains for 5 days there are 75 wildflowers growing.
• There are 75 wildflowers growing.
• With 5 inches of rain, there are 75 wildflowers growing.

The function h(t) represents the height in inches of a plant after t weeks. What does the notation h(4) = 5 mean?

• After 5 week the plant is 4 inches tall
• The plant grows at a rate of 5/4 inch per week
• After 4 weeks the plant is 5 inches tall
• The plant grows at a rate of 1 inch per week

The function c(m) = 1.45m + 3.50 represents the cost of a taxi for m miles.
What does c(7) represent?

• A cost of $7 to ride the taxi
• The cost to ride 7 miles
• The minimum distance to ride a taxi
• The minimum cost of a taxi

The function c(m) = 1.45m + 3.50 represents the cost of a taxi for m miles.
What does c(m) represent?

• Total Cost of a taxi
• Total Miles in taxi

Derek works at Subway making $9.25 an hour.  The function d(x)=9.25x tells us how much money Derek makes after x hours of working.  What is the meaning of d(4)=37?

• After 4 hours of work, Derek makes $37.
• Derek needs $4 more to have $37 total.
• After working for 4 days, Derek makes $37 total.
• After 4 hours of work, Derek now makes $37 an hour instead of $9.25.

Ms. Brackemyer is collecting pencils.  The function p(x)=5x+12 tells us the total amount of pencils Ms. Brackemyer has after collecting for x number of days.  What is the meaning of p(8)=52?

• Ms. Brackemyer starts with 8 pencils and ends with 52.
• After 8 days, Ms. Brackemyer has 52 pencils.
• Ms. Brackemyer starts with 52 pencils and gets 4 more every day.
• Every day, Ms. Brackemyer gets 4 new pencils until she has 52.

A company is selling bubble gum.  The function g(x)=3x+4 tells the company how much to charge if someone buys x packages of bubble gum.  Find g(8) and tell what it means within the context of the problem.

• g(8)=8.  This means that after 8 packages of gum, the company makes $8.
• g(8)=42.  This means that 8 packages of gum costs $42.
• g(8)=28.  This means that 8 packages of gum costs $28.
• g(8)=24.  This means that 8 packages of gum costs $24.

Rewrite in function notation: (3, -2)

• F(-2) = 3
• F(3) = -2

What is the definition of function?

• Has inputs and outputs
• Every input has only ONE output
• Inputs have different outputs every time
• x-values and y-values