Chapter 1: Problem 1
(a) Find an equation for the family of linear functions with slope 2 and sketch several members of the family. (b) Find an equation for the family of linear functions such that \(f(2)=1\) and sketch several members of the family. (c) Which function belongs to both families?
Short Answer
Expert verified
The function is \( f(x) = 2x - 3 \).
Step by step solution
01
Finding the Family of Linear Functions with Slope 2
A linear function can be represented as \( f(x) = mx + c \), where \( m \) is the slope. Given the slope of 2, the general equation becomes \( f(x) = 2x + c \). This equation represents a family of linear functions with varying \( c \) values, determining the different y-intercepts.
02
Sketching Members of the Family
To sketch members of the family, select different values for \( c \) such as 0, 1, and -1. For \( c = 0 \), the function is \( f(x) = 2x \). For \( c = 1 \), it's \( f(x) = 2x + 1 \), and for \( c = -1 \), it's \( f(x) = 2x - 1 \). The graphs will be parallel lines with the same slope but different y-intercepts.
03
Finding the Family of Linear Functions where f(2) = 1
This condition means \( f(2) = 2m + c = 1 \). We rearrange to find \( c = 1 - 2m \). Thus, the equation for this family is \( f(x) = mx + (1 - 2m) \). This represents a set of lines crossing the point (2, 1), differing by slope \( m \).
04
Sketching Members of this Family
Choose different slopes, say \( m = 0 \), \( m = 1 \), and \( m = -1 \). For \( m = 0 \), \( f(x) = 1 \). For \( m = 1 \), \( f(x) = x - 1 \). For \( m = -1 \), \( f(x) = -x + 3 \). These lines will all cross the point (2, 1).
05
Finding the Intersection of Both Families
A function belonging to both families must satisfy both conditions: a slope of 2 and passing through (2, 1). From the second family equation, substitute \( m = 2 \) into \( c = 1 - 2m \), yielding \( c = 1 - 4 = -3 \). Thus, the function is \( f(x) = 2x - 3 \).
06
Verify and Sketch the Intersection Function
Verification: This function has a slope of 2, and substituting \( x = 2 \), we find \( f(2) = 2(2) - 3 = 1 \), confirming the point (2, 1). Graphing \( f(x) = 2x - 3 \) shows it satisfies both criteria.
Unlock Step-by-Step Solutions & Ace Your Exams!
-
Full Textbook Solutions
Get detailed explanations and key concepts
-
Unlimited Al creation
Al flashcards, explanations, exams and more...
-
Ads-free access
To over 500 millions flashcards
-
Money-back guarantee
We refund you if you fail your exam.
Over 30 million students worldwide already upgrade their learning with 91Ó°ÊÓ!
Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Understanding the Slope of a Line
The slope of a line is a measure of its steepness. It tells us how much the line rises or falls as it moves from left to right. In the formula for a linear function, written as \( f(x) = mx + c \), the variable \( m \) represents the slope.
- If the slope \( m \) is positive, the line rises as you move from left to right.
- If \( m \) is negative, the line falls as you move from left to right.
- A zero slope means the line is horizontal.
- An undefined slope (dividing by zero in the calculation of slope) means the line is vertical.
Grasping the Y-Intercept
The y-intercept is the point where the line crosses the y-axis. In the equation \( f(x) = mx + c \), the y-intercept is represented by \( c \). This is the value of \( y \) when \( x \) is zero. Knowing the y-intercept helps us understand where the line sits vertically on a graph.When drawing a linear function, the y-intercept gives you a starting point. You can then use the slope to determine the direction and steepness of the line from that point. The y-intercept is crucial for sketching the graph of a linear function, which can be different for every member of a family of lines.
Exploring Point-Slope Form
The point-slope form is another way to write the equation of a line when you know the slope and a specific point on the line. The formula is \( y - y_1 = m(x - x_1) \), where \( m \) is the slope and \( (x_1, y_1) \) is a point on the line.This form is particularly useful when you know certain specific points that the line must pass through, such as \( f(2) = 1 \) in the problem presented. It allows you to quickly find the equation of a line by adjusting the slope and translating through different points.With the point-slope form, you can easily apply real-world data, finding the proper line equations that meet given conditions.
Understanding Parallel Lines
Parallel lines have the same slope but different y-intercepts. This means they never intersect, remaining equidistant forever. In practical terms, two lines \( y = mx + c_1 \) and \( y = mx + c_2 \) are parallel if both have the same slope \( m \), but different intercepts \( c_1 \) and \( c_2 \).This concept was demonstrated in the exercise where you have a family of lines all with a slope of 2 but varying y-intercepts. When graphing, these lines appear as parallel, reinforcing our understanding of how the slope and y-intercept influence the position of a line.Understanding the principle of parallelism in lines is crucial in geometry and various applications, ensuring precise calculations and system interpretations.