Consider the function f ( x ) = 9 x . determine the average rate of change (aroc) of f over the following intervals of x . from x = 2 to x = 3.5 . aroc: from x = 3.5 to x = 5 . aroc: from x = 5 to x = 6.5 . aroc: consider the three average rates of change you computed in part (a). are these average rates of change increasing, decreasing, or some combination of both? increasing decreasing some combination of both over the interval from x = 2 to x = 6.5 , does f have positive concavity, negative concavity, or some combination of both? positive concavity negative concavity some combination of both