Chapter 4: Problem 123
Write the domain in interval notation. $$ s(x)=\ln (\sqrt{x+5}-1) $$
Short Answer
Expert verified
( -4, \infty )
Step by step solution
01
Understand the Argument of the Logarithm
Identify the part of the function inside the logarithm, which is \( \sqrt{x+5} - 1 \). The domain of a logarithmic function is defined only when its argument is positive.
02
Set the Argument Greater Than Zero
To ensure the logarithm is defined, set \( \sqrt{x+5} - 1 > 0 \) and solve for \( x \).
03
Isolate the Square Root
Add 1 to both sides of the inequality: \( \sqrt{x+5} > 1 \).
04
Square Both Sides
Eliminate the square root by squaring both sides: \( x+5 > 1 \).
05
Solve for x
Subtract 5 from both sides: \( x > -4 \). Thus, the domain of the function must be all \( x \) values greater than \( -4 \).
06
Write in Interval Notation
The domain in interval notation is \(( -4, \infty ) \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Interval Notation
Interval notation is a way to represent the set of all numbers between two endpoints.
You use parentheses '()' to indicate that an endpoint is not included in the interval and brackets '[]' to show that an endpoint is included.
For example, the interval \( (a, b) \) means all numbers greater than \( a \) but less than \( b \), excluding \( a \) and \( b \).
For the exercise provided, we determined the domain of the function \( s(x) = \ln(\sqrt{x+5} - 1) \) and wrote it as \( (-4, \infty) \).
This means \( x \) can be any number greater than \( -4 \) but not equal to it.
You use parentheses '()' to indicate that an endpoint is not included in the interval and brackets '[]' to show that an endpoint is included.
For example, the interval \( (a, b) \) means all numbers greater than \( a \) but less than \( b \), excluding \( a \) and \( b \).
For the exercise provided, we determined the domain of the function \( s(x) = \ln(\sqrt{x+5} - 1) \) and wrote it as \( (-4, \infty) \).
This means \( x \) can be any number greater than \( -4 \) but not equal to it.
Logarithmic Functions
Logarithmic functions are the inverse of exponential functions.
The natural logarithm, denoted as \ln(x)\, is the logarithm to the base \( e \) (where \( e \) is approximately 2.718).
For a logarithmic function to be defined, its argument must be greater than zero.
The function \( s(x) = \ln(\(\sqrt{x+5} - 1\)) \) means we're looking at the logarithm of the expression \( \sqrt{x+5} - 1 \).
This expression inside the logarithm needs to be positive for the function to exist.
Therefore, we solve the inequality \( \sqrt{x+5} - 1 > 0 \) to find the domain.
The natural logarithm, denoted as \ln(x)\, is the logarithm to the base \( e \) (where \( e \) is approximately 2.718).
For a logarithmic function to be defined, its argument must be greater than zero.
The function \( s(x) = \ln(\(\sqrt{x+5} - 1\)) \) means we're looking at the logarithm of the expression \( \sqrt{x+5} - 1 \).
This expression inside the logarithm needs to be positive for the function to exist.
Therefore, we solve the inequality \( \sqrt{x+5} - 1 > 0 \) to find the domain.
Domain Restrictions
Domain restrictions tell us which values of \( x \) are allowed for a function.
For logarithmic functions, the argument inside the log must always be positive.
Let's break down the steps to determine the domain of \( s(x) = \ln(\(\sqrt{x+5} - 1\)) \):
For logarithmic functions, the argument inside the log must always be positive.
Let's break down the steps to determine the domain of \( s(x) = \ln(\(\sqrt{x+5} - 1\)) \):
- First, identify the argument: \( \sqrt{x+5} - 1 \).
- Then, set the argument greater than zero: \( \sqrt{x+5} - 1 > 0 \).
- Add 1 to both sides: \( \sqrt{x+5} > 1 \).
- Square both sides: \( x + 5 > 1 \).
- Solve for \( x \): \( x > -4 \).