Answer:
The rate of change for the given function is 6.
Explanation:
Given function is:

The interval on which we have to find the rate of change is:
1≤x≤2
Here
a = 1
b = 2
We have to find the values of function on both points
Putting 1 in place of input (x)

Putting x = 2

The rate of change is calculated by using the following formula

Hence,
The rate of change for the given function is 6.