What is the average value of latex: y=\tan\left(\frac{x^2}{9}\right) y = tan ⁡ ( x 2 9 ) on the closed interval [1.25, 2]?

For this case we have the following function:
 
 The average rate of change is given by:
 
 Evaluating the function for the given interval we have:
 For x = 1.25:
 
 
 For x = 2:
 
 
 Then, replacing values we have:
 
 
 
 the average value of on the closed interval [1.25, 2] is:
 

Bis the correct answer