You can
put this solution on YOUR website! .
The average rate of change of the function f(x) from x= 1 to x= 4 is equal to
by the definition.
In other words, you need to calculate the values of the function at x= 4 an at x= 1.
Then take the difference of these values
and then divide the difference by the length of the interval, which (the length) is 4-1 = 3 in your case.