推 StellaNe : 範圍內嚴格遞減 極值在端點 02/25 11:58
If the operating costs of a delivery truck are 16+(x/2) cents per mile
when the truck travels x mi/hr and the driver earns $10 per hour,
what is the most economical speed, to the nearest integer, to operate
the truck on a 200-mile-long road, where the minimum speed is 50 mi/hr
and the maximum speed is 75 mi/hr ? (A)50 (B)56 (C)63 (D)75
我的算式是 10．(200/x) - 200．[16+(x/2)]．(1/100)，50<=x<=75
然後再去算極值 但好像怪怪的 找不出答案 不曉得算式是否有問題
先謝謝熱心回答的版友
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