An automobile starts from rest and travels down a straight section of road. The distance [math] (in feet) of the car from the starting position after [math] seconds is given by [math]

(a) Find the instantaneous velocity (in feet per second) at [math] seconds.

Instantaneous velocity at [math] is ft/s.

(b) Find the instantaneous velocity in (feet per second) at [math] seconds.

Instantaneous velocity at [math] is ft/s.