The height (in feet) of a rocket from ground level is given by the function f (t) = - 16t2 + 220t. What is the instantaneous velocity of the rocket 12 seconds after its launch?

-164 ft/second.

Step-by-step explanation:

The instantaneous velocity is given by the derivative;

f (t) = - 16t^2 + 220t

V = f' (t) = - 32t + 220

So at 12 seconds:

V = - 32*12 + 220

= - 164 ft/second (It is negative because it is descending).