helpp (1 Viewer)

ffdsfd · Nov 19, 2016

A truck travels 1500 km at an hourly cost given by s2 + 9000 cents where s is the average speed of the truck.

b)Find the speed that minimises the cost of the trip.
(c) Find the cost of the trip to the nearest dollar.

InteGrand · Nov 19, 2016

ffdsfd said:
A truck travels 1500 km at an hourly cost given by s2 + 9000 cents where s is the average speed of the truck.

b)Find the speed that minimises the cost of the trip.
(c) Find the cost of the trip to the nearest dollar.

Here's how to set it up.

$\noindent I'm assuming $s$ is in km/h. The time of the trip when the average speed is $s$ is $\frac{1500}{s}$ (in hours). So the total cost is $\frac{1500}{s}\times \left(s^2 + 9000\right)$ cents. So just find the $s^{\star} >0$ that minimises this function, and evaluate it at this $s^{\star}$ to get the minimum cost (and convert to dollars).$

helpp (1 Viewer)

ffdsfd

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InteGrand

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