Chapter 1: Problem 9
Sketch a graph of the given logarithmic function. $$ f(x)=\log _{2}(x-1) $$
Short Answer
Expert verified
Sketch the graph with a vertical asymptote at \( x = 1 \), it passes through points \( (2, 0) \) and \( (3, 1) \), and increases for \( x > 1 \).
Step by step solution
01
Identify the Function Type
The given function is a logarithmic function in the form of \( f(x) = \log_{2}(x-1) \). This indicates a log base 2 function shifted to the right by 1 unit.
02
Determine the Domain
Since \( \log_{2}(x-1) \) is only defined for positive arguments, the inside of the log must be greater than zero: \( x-1 > 0 \). Solving this inequality, we find that the domain of the function is \( x > 1 \).
03
Find the Vertical Asymptote
Logarithmic functions have a vertical asymptote where the argument of the log equals zero. Setting \( x-1 = 0 \) gives \( x = 1 \). Therefore, there is a vertical asymptote at \( x = 1 \).
04
Identify Key Points
Find key points that will help in sketching the graph:1. At \( x = 2 \), \( f(x) = \log_{2}(2-1) = \log_{2}(1) = 0 \).2. At \( x = 3 \), \( f(x) = \log_{2}(3-1) = \log_{2}(2) = 1 \).These points help define the shape of the graph as it increases to the right of the asymptote.
05
Sketch the Graph
Using the details from previous steps:1. Draw a vertical line (asymptote) at \( x = 1 \).2. Plot the key points: \( (2, 0) \) and \( (3, 1) \).3. Sketch a curve starting from close to the asymptote at \( (1, -\infty) \), passing through the key points, and increasing to the right.
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.
Domain of a Function
Understanding the domain of a function is crucial, as it tells us all the possible inputs (x-values) that the function can accept. For the logarithmic function given, \( f(x) = \log_{2}(x-1) \), the domain is determined by the expression inside the logarithm. Because the logarithm of a non-positive number is undefined, the argument \( x-1 \) must be greater than zero. To find this, simply solve the inequality:
- \( x - 1 > 0 \)
- \( x > 1 \)
Vertical Asymptote
A vertical asymptote in a graph signifies a line that the graph approaches but never touches or crosses. For logarithmic functions, vertical asymptotes occur where the argument inside the logarithm equals zero. In our function \( f(x) = \log_{2}(x-1) \), this happens when \( x-1 = 0 \):
- Solve for x: \( x = 1 \)
Key Points in Graphing
Key points on a graph can help you outline the function's shape and see how it behaves around important x-values. For \( f(x) = \log_{2}(x-1) \), finding specific points for x that are easy to calculate provides a clear guide in drawing the graph.Some useful points to consider are:
- At \( x = 2 \): \( f(x) = \log_{2}(2-1) = \log_{2}(1) = 0 \). This results in the point (2, 0) on the graph.
- At \( x = 3 \): \( f(x) = \log_{2}(3-1) = \log_{2}(2) = 1 \). This gives us the point (3, 1).
Transformation of Functions
Transformations shift, stretch, or compress the graph of a function in different ways. In the function \( f(x) = \log_{2}(x-1) \), the formula itself signals a transformation:
- The \( -1 \) within the log's argument shifts the graph 1 unit to the right.
- There are no vertical shifts or reflections as there are no added or subtracted terms outside the logarithm, or negative signs altering the function's direction.