题库搜索>问题求解PS-17778
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A certain manufacturer uses the function C(x)=0.04x2 -8.5x+25,000 to calculate the cost,in dollars, of producing x thousand units of its product. The table above gives values of this cost function for values of x between 0 and 50 in increments of 10. For which of the following intervals is the average rate of decrease in cost less than the average rate of decrease in cost for each of the other intervals?
分析A选项
分析B选项
分析C选项
分析D选项
分析E选项
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暂无雷哥网文字解析
不用硬算，画一个向上抛物线，越靠近中心，减少的速率越慢。公式可以算出这个抛物线的对称轴（大于100），而40-50区间是最靠近中心轴的，选E
小良冠二郎
一元二次方程 Slope: ax + by + c = 0
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2023-05-12 22:21:54
小良冠二郎
一元二次方程 Slope: ax + by + c = 0
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0
回复
2023-05-12 22:21:54
小良冠二郎
一元二次方程 Slope: ax + by + c = 0
0
0
回复
2023-05-12 22:21:53
小良冠二郎
一元二次方程 Slope: ax + by + c = 0
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0
回复
2023-05-12 22:21:53
小良冠二郎
一元二次方程 Slope: ax + by + c = 0
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0
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2023-05-12 22:21:52
1021673uqtd
在区间单调递减，问平均下降率最小，就是斜率绝对值最小，画图看
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2022-08-05 15:34:21
高杨
最简单的想法：规模效应，产量越大一般成本会被平均掉所以降低，秒选E，-b/2a验证后选E
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2021-11-16 16:52:12
豆果的杏力蛋
抛物线对称轴-b/2a=8.5/0.08>100，且抛物线开口向上，在【0,50】区间单调递减
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2021-08-29 20:53:08
488556dmss
求导出来是斜率，0.08x-8.5中随x增大，斜率绝对值减小，降幅减小。所以之前回答的降幅增大的各位在想啥，但凡画个图也不会看错啊。
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2021-07-08 09:36:09
William(GMAT 750+)
x越大，降幅越大
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2021-03-06 18:35:17
1542363ucik
降幅真的可以用导数算吗。
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2021-02-04 17:29:21
要去lse回复1542363ucik
没问题
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2021-10-20 20:50:02
Mariposa爱学习
完了 我知道怎么求导。 但是忘记求导出来干嘛了 gap一年啥都忘了。。。。
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2020-12-22 16:11:51
小仙女怡
这里问的是降幅，把函数求导后得0.08x-8.5，x越大，降幅越大
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2020-08-27 10:06:57
265611yraoq
画出图像即可，可知道 斜线倾斜程度逐渐平缓，可知道C(X)降低的越来越慢，选E
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2019-10-27 20:39:51
374729so
把每个间隔之差算出来，最小的就是答案
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2019-10-20 21:21:12
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问题求解PS
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GMAT难题300合集
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