Maximum and Minimum on an Interval Question

Question

The fuel efficiency, E, in litres per 100 kilometres, for a car driven at speed v, in km h, is

E(v)=1600v/v² +6400

a) If the speed limit is 100 km h, determine the legal speed that will maximize the fuel efficiency.

b). Repeat part a., using a speed limit of 50 km h.

c). Determine the speed intervals, within the legal speed limit of 0 km/h to 100 km/h, in which the fuel efficiency is increasing.

d). Determine the speed intervals, within the legal speed limit of 0 km/h to 100 km/h, in which the fuel efficiency is decreasing.

Im having trouble figuring out how to solve all of these. I can find the max and min on other equations but this one is giving me trouble

Answer 1

Are you sure the equattion is written correctly? It should just have 1600/v in it.