Question

Identifying Linear Functions from Real-World Situations
Which situations represent linear functions? Check all that apply.
The temperature rises and falls over the course of a day. Temperature is a function of time.
A baseball is hit into the outfield. The height of the ball is a function of time.
A car goes 55 mph on the highway. Distance is a function of time.
A child grew 2 inches this year and 1 inch last year. Height is a function of time.
A movie director makes 2 movies per year. The number of movies is a function of the years.

Answer 1

Linear functions have a constant rate of change (y = mx + b). Which fit that?

- Temperature rises and falls — Not linear (rate changes).
- Baseball height — Not linear (projectile motion is quadratic).
- Car at 55 mph — Linear (distance increases at constant 55 mi/hr).
- Child grew 2 in one year and 1 in another — Not linear (rate changed).
- Director makes 2 movies per year — Linear (movies increase at constant 2 per year).

So the linear ones are: the car distance and the director's movie count.