知识点地图 / 代数

Interpreting & Using Linear Models

线性建模・解释与预测

解释线性模型中系数的含义,并在合理范围内进行预测。

01 / UNDERSTAND

这部分需要会什么?

  • 结合单位解释线性模型中的系数
  • 利用模型预测并理解交点
  • 区分模型的代数范围与实际适用范围

核心概念与公式

在 \(y=mx+b\) 中,\(m\) 表示 \(x\) 每增加 1,预测的 \(y\) 增加 \(m\);若 \(m<0\),表示减少。\(b\) 是输入为零时的模型值,只有 \(x=0\) 在情境中有意义时,才能解释为实际初始值。

两个费用模型的交点表示费用相等的输入;零点表示模型输出降到零的输入。利用观测范围内的输入作预测叫插值;超出范围的外推需要格外注意模型是否仍然适用。

做题时怎样使用

  1. 先读清变量定义,例如 \(t\) 是某年之后的年数还是具体年份
  2. 把斜率翻译成带有“每”和单位的句子
  3. 代入预测输入,并检查是否落在合理的时间、数量或测量范围内

容易混淆的地方

模型中的负斜率表示每单位减少固定量,不是减少固定百分比。若时间单位从年变为月,系数也要随之改变。

02 / CONNECT

用一个例题串起方法

知识点教学例题
水箱余水量满足 \(V=120-8t\),其中 \(V\) 以升计、\(t\) 以分钟计。解释系数并求水箱何时排空。
展开解题思路 +

初始有 120 升水,每分钟减少 8 升。令 \(V=0\),得 \(t=15\)。排空前模型的实际时间范围为 \(0\le t\le15\),不能把负水量当作真实结果。

03 / PRACTISE

本知识点题库

先独立作答,再查看答案与解析。

205 道题目
找到 205 道题目重置筛选
线性建模・解释与预测进阶

\( s=40+3t \) 
The equation gives the speed s, in miles per hour, of a certain car t seconds after it began to accelerate. What is the speed, in miles per hour, of the car 5 seconds after it began to accelerate?
原库参考解析
Bluebook试题10 · 原库模块 1 · Q2作答 ↗
线性建模・解释与预测挑战

Caleb used juice to make popsicles. The function \( f\left(x\right)=-5x+30 \) approximates the volume, in fluid ounces, of juice Caleb had remaining after making x popsicles. Which statement is the best interpretation of the y-intercept of the graph of \( y=f\left(x\right) \) in the xy-plane in this context?
原库参考解析
Bluebook试题10 · 原库模块 3 · Q3作答 ↗
线性建模・解释与预测进阶

题目图表
A certain open star cluster contains M-type stars and K-type stars. The estimated total mass of M-type and K-type stars in this open star cluster is 127,882 quettagrams. The graph shown models the possible combinations of the number of M-type stars, x, and K-type stars, y, that could be in this open star cluster if all the M-type stars have the same estimated mass and all the K-type stars have the same estimated mass. Based on the graph, which of the following is closest to the estimated mass, in quettagrams, of each M-type star in this cluster?

原库参考解析
Bluebook试题11 · 原库模块 1 · Q19作答 ↗
线性建模・解释与预测挑战

题目图表
The graph shows the estimated boiling point  , in degrees Celsius, of a normal paraffin with a molecular weight of x grams per mole, where \( 1\le x\le280 \). Which statement is the best interpretation of the point (149.02, 186.05)?
原库参考解析
Bluebook试题11 · 原库模块 3 · Q5作答 ↗
线性建模・解释与预测进阶

5G +45R = 380
At a school fair, students can win colored tokens that are worth a different number of points depending on the color. One student won G green tokens and R red tokens worth a total of 380 points.The given equation represents this situation.How many more points is a red token worth than a green token?
原库参考解析
Bluebook试题1 · 原库模块 1 · Q15作答 ↗
线性建模・解释与预测进阶

题目图表
The graph represents the total charge, in dollars, by an electrician for x hours of work. The electrician charges a onetime fee plus an hourly rate. What is the best interpretation of the slope of the graph?
原库参考解析
Bluebook试题1 · 原库模块 1 · Q5作答 ↗
线性建模・解释与预测挑战

A neighborhood consists of a 2-hectare park and a 35-hectare residential area. The total number of trees in the neighborhood is 3,934.The equation 2x +35y = 3,934 represents this situation. Which of the following is the best interpretation of x in this context?
原库参考解析
Bluebook试题1 · 原库模块 3 · Q5作答 ↗
线性建模・解释与预测挑战

Keenan made 32 cups of vegetable broth.Keenan then filled x small jars and y large jars with all the vegetable broth he made.The equation 3x +5y = 32 represents this situation. Which is the best interpretation of 5y in this context?
原库参考解析
Bluebook试题2 · 原库模块 3 · Q11作答 ↗
线性建模・解释与预测挑战

F(x)=

\(\frac{9}{5}\)
(x - 273.15) + 32
The function F gives the temperature, in degrees Fahrenheit, that corresponds to a temperature of x kelvins.If a temperature increased by 2.10 kelvins, by how much did the temperature increase, in degrees Fahrenheit?
原库参考解析
Bluebook试题2 · 原库模块 3 · Q14作答 ↗
线性建模・解释与预测挑战

Caleb used juice to make popsicles.The function f(x) = -5x +30 approximates the volume, in fluid ounces, of juice Caleb had remaining after making x popsicles. Which statement is the best interpretation of the y-intercept of the graph of y = f(x) in the xy-plane in this context?
原库参考解析
Bluebook试题2 · 原库模块 3 · Q5作答 ↗
线性建模・解释与预测进阶

w(t)= 300- 4t
The function w models the volume of liquid, in milliliters, in a container t seconds after it begins draining from a hole at the bottom. According to the model, what is the predicted volume, in milliliters, draining from the container each second?
原库参考解析
Bluebook试题3 · 原库模块 1 · Q12作答 ↗
线性建模・解释与预测进阶

A bus is traveling at a constant speed along a straight portion of road. The equation d = 30t gives the distance d, in feet from a road marker, that the bus will be t seconds after passing the marker. How many feet from the marker will the bus be 2 seconds after passing the marker?
原库参考解析
Bluebook试题3 · 原库模块 1 · Q1作答 ↗