Step-by-step explanation
The average rate of change of a given function f(x) in the interval (a,b) is given by the following formula:

This is valid only if f(x) is defined at x=a and x=b.
In our case the interval is (-2,5) and the function is:

So we need to find f(-2) and f(5):

Then the average rate of change of this function in the interval (-2,5) is given by:

Answer
Then the answer is that the Average Rate of Change of f(x) in (-2,5) is 8.