Answer:
The average rate of change of f(x) = x + 6 on [4,9) is 1.
Explanation:
Given a function y, the average rate of change S of
in an interval
will be given by the following equation:

In this problem, we have that:

Interval [4,9]
Continuous function(no denominator or even root), this is why i can consider 9 a part of the interval for the calculation. So
.
So

The average rate of change of f(x) = x + 6 on [4,9) is 1.