So, we first have to find the two values at the end points of the interval:\
[tex] y=2^2+5*2=14\\
y=8^2+5*8=104 [/tex]
Then, from 2 to 8 there are 9 numbers, so to find the average rate of change we can subtract 104 from 14 and divide it by 9:
[tex] \frac{104-14}{9}=\frac{90}{9}=10 [/tex]
Our average rate of change is 10.
