The driver of a car travelling downhill on a road applies the brakes. The speed s of the car in km h-1, t seconds after the brakes were applied, is given by
s(t)=-4t2 + 12t + 80.
a How fast was the car travelling when the driver applied the brakes?
b After how many seconds was the speed of the car 88 kmh-1? Can you explain
your answer?
< After how many seconds did the car reach its maximum speed?
d What was the maximum speed reached?