tion isThe rate of change of a function f(x) at the interval [a, b] is
Since the given function is
Since the given interval is [1, (1 + h)], then
a = 1
b = (1 + h)
Substitute x by a and b and use the rule above
Substitute them in the rule above
Take 3 as a common factor from the numerator
The rate of change of the given function is