3.1. 导言:权力、一夫多妻制和合理功能

章节大纲

• 选择节常规

  折叠 展开

  常规

  全部折叠 展开全部

  • 选择活动新闻通告

    

    新闻通告 讨论区
• 选择节导言:权力、一夫多妻制和合理职能

  折叠 展开

  导言:权力、一夫多妻制和合理职能

  

  播放段落

  Polynomial functions are t he most useful functions in the branch of mathematics that supports calculus. These functions are first studied in algebra in the form of  the equation of a straight line. For example, consider the sample data for pollen levels  in Austin, Texas, during March of 2016:
  ::多元函数是支持微积分的数学分支中最有用的函数。 这些函数首先以直线方程式的形式在代数中进行代数研究。 例如,考虑2016年3月得克萨斯州奥斯汀的花粉浓度样本数据:

  Date	播放段落 Pollen Level  ( grains per cubic meter of air) ::电极水平(每立方米空气的谷物量)
  3/3/2016	10.7
  3/4/2016	9.3
  3/5/2016	8.9

  播放段落

  An examination of the data shows that the pollen level  decreases at a fairly constant rate. For any point in time within these dates, the linear function  $\begin{array}{r}P(t)=-0.9t+11.43,\end{array}$  where $\begin{array}{r}t\end{array}$  is the number of days since 3/2/2016, is a good approximation of the pollen level in Austin.
  ::对数据的检查表明,花粉水平以相当固定的速度下降。在这些日期的任何时间点上,线性函数P(t)0.9t+11.43(t)是自3/2/2016以来的天数)与奥斯汀的花粉水平相当接近。

     

   

  播放段落

  For example, if the pollen level is 10.7 at 8 p.m. on the evening  of 3/3/2016, w e can then determine that  $\begin{array}{r}t=1.5\end{array}$  is the number of days that have passed since 8 a.m. on 3/2/2016, and substitute into the linear function.  $\begin{array}{r}P(1.5)=(-0.9)(1.5)+11.43\end{array}$  calculates to $\begin{array}{r}P(1.5)=10.083\end{array}$ , which provides a good estimate for the level at 8 p.m. From the graph, it appears that the pollen level would be about 10.083 because the three data points show a  steady decrease. Linear functions, then, are models that provide predictive tools for values within an interval or for the short term.
  ::例如,如果花粉水平为3/3/2016晚8时10.7分,那么我们可以确定t=1.5是自3/2/2016凌晨8时以来经过的天数,并替代线性函数。 P(1.5)=(-0.9)(1.5)+11.43计算为P(1.5)=1.083,这很好地估计了8时的水平。 从图中可以看出,花粉水平大约为10.083,因为三个数据点显示持续下降。那么线性函数是提供间隔内或短期内数值预测工具的模型。

  播放段落

  Consider the data for the pollen level  over a longer term:
  ::考虑长期的花粉水平数据:

  

  播放段落

  Over a longer period of time, the pollen level   does not follow a linear pattern . The pollen level  increases, decreases, and reaches maximum and minimum values. Also, for any day, the pollen level  is defined. Pollen levels  have been in the atmosphere for years, and they will continue for years.
  ::在更长的时间内,花粉水平不遵循线性模式。 花粉水平增加、 减少并达到最高值和最低值。 此外, 花粉水平在任何一天中都有定义。 花粉水平在大气中已经存在多年, 并且会持续多年 。

  播放段落

  Polynomial functions can be adjusted to measure data. This class of functions can measure behavior while at the same time be predictable. Their domain is the set of all real numbers, so they can be used for any dataset. 
  ::多边函数可以调整以测量数据。 此函数类别既可以测量行为, 同时可以预测。 它们的域是所有真实数字的集合, 这样它们就可以用于任何数据集 。

  播放段落

  This chapter studies the characteristics of polynomial functions. These functions are introduced with the quadratic function. Their domain, range, and behavior are developed along with real-world examples. The chapter concludes with a study of the family of a closely related function: the rational function.
  ::本章研究多元函数的特性。 这些函数与二次函数一起引入。 它们的领域、范围和行为与现实世界的例子一起发展。 本章最后对一个密切相关的函数的家庭进行了一项研究: 理性函数 。