- 4 Suppose f(x) = Write an expression in terms of x and h that represents the x + 6 average rate of change of f over any interval of length h. [That is, over any interval (z, x + h).] Simplify your answer as much as possible. Preview Box 1: Enter your answer as an expression. Example: 3x 2+1, x/5, (a+b)/c Be sure your variables match those in the question Points possible: 1 License Unlimited attempts