... closer to zero, the average rate of change over the tiny interval approaches the instantaneousrate of change at x = a. The instantaneous rate of change of f at x = a ≈f (a +h) − f (a) (a + h) − a for ... through (a, f (a) )and (b, f(b)).The instantaneous rate of change of f at x = a can be approximated by the averagerate of change of f on [a, a + h] for h very close to zero. As h gets closer and closer to ... velocity was greater than −80 ft/sec, then we said that it was greater than 65 .6 ft/sec, and now we have determined that it is greater than 64 . 16 ft/sec.As a lid on the value of the instantaneous...