Rates of Change
Rate of Change of a Function: How quickly the output-value of a function changes per change in the input-value.
Examples:
The volume of the balloon is increasing by five cubic inches per second
The water level in the reservoir is decreasing by one foot per week
The slope of the graph is 32.
To the left is a graph of the number of active twitter users as a function of time.
A normal person asks: "When was twitter growing the fastest?"
An mathematician asks: "When was the rate of change of the number of twitter users greatest?"