Question 169103
the selling price of a steer in x days is the weight (135+3.5x) times the unit price (1.65-.01x)


the cost to keep the steer for x days is .8x


the profit is the selling price minus the cost __ (135+3.5x)(1.65-.01x)-.8x __ this is the function to maximize


FOILing __ 222.75+5.775x-1.35x-.035x^2-.8x = p __ -.035x^2+3.625x+222.75 = p


the maximim is on the axis of symmetry __ the general eqn is x=-b/(2a)
__ in this case __ x=-3.625/[2(-.035)] __ x=51.8 (approx)


the steer should be sold on the 52nd day to maximize profit