Thank you for the opportunity to help you with your question! the solution is as such:

Whenever the rate of change is required for a function with f(x) and f(x+h) , then the rate is equal to its first differential .

So here the rate is f' (x) at x= 2

So f'(x) = 8x and at x= 2 it equals to 16

Please let me know if you need any clarification. I'm always happy to answer your questions.awaiting a positive feedback. It was lovely helping you. Looking forward to help you again. A positive feedback awaited thank you.