the owner of a video store has determined that the cost C, in dollars, of operating the store is approximately given by C(x)=2x^2-18x+670, where x is the number of videos rented daily. find the lowest cost to the nearest dollar.

Question

the owner of a video store has determined that the cost C, in dollars, of  operating the store is approximately given by C(x)=2x^2-18x+670, where x is the number of videos rented daily. find the lowest cost to the nearest dollar.

oobleck · Answer

The graph is just a parabola. As always, the vertex is at
x = -b/2a = 18/4
C(9/2) = 629.50

I find this unreasonable. Who could stay in business renting just 4 or 5 videos daily? Maybe x is in hundreds.