What is the rate of change from x = π to x = 2π? 8 over pi pi over 8 negative 8 over pi negative pi over 8

We can model the function in that interval as a straight line of negative slope.
 We have then that the average rate of change in that interval is given by:
 r = (y2-y1) / (x2-x1)
 Substituting values:
 r = (- 4-4) / (2π-π)
 Rewriting we have:
 r = -8 / π
 
 the rate of change from x = π to x = 2π is:
 r = -8 / π