Step-by-step explanation:
The given expression is
Notice that and are elements of the domain and and are elements of the range.
Observe the notation used, an element of the range is always written like where is an element of the domain.
Also, notice that this expression is using two pair of coordinates, which are and .
On the other hand, the definition of average rate of change is
Where and .
Having said that, the given expression represents an average rate of change in the interval, where the rate is 2. The right answer is the third option.