Chapter 9: Problem 29
Specify the domain for each of the functions. $$f(s)=\sqrt{4 s-5}$$
Short Answer
Expert verified
The domain of the function is \( \left[\frac{5}{4}, \infty\right) \).
Step by step solution
01
Understand the Function and Its Requirements
The function given is \( f(s) = \sqrt{4s - 5} \). Since the function involves a square root, the expression inside the square root must be non-negative. This is because the square root of a negative number is not defined in the set of real numbers.
02
Set the Expression Inside the Square Root to be Non-Negative
To ensure that the expression inside the square root is non-negative, set up the inequality: \[ 4s - 5 \geq 0 \]This inequality ensures that 4s - 5 is zero or positive.
03
Solve the Inequality for s
Solve the inequality from Step 2:\[4s - 5 \geq 0 \4s \geq 5 \s \geq \frac{5}{4}\]The solution \( s \geq \frac{5}{4} \) are the values for which the function is defined.
04
Write the Domain in Interval Notation
The domain of the function is all real numbers \( s \geq \frac{5}{4} \). In interval notation, this is expressed as:\[ \left[\frac{5}{4}, \infty\right) \]This represents all real numbers starting from \( \frac{5}{4} \) to infinity.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Inequality solving
Solving inequalities is a fundamental skill in mathematics. It involves finding the set of values that satisfy a given inequality relation. For the function \( f(s) = \sqrt{4s - 5} \), we need 4s - 5 to be non-negative because the square root function is only defined for non-negative numbers.
To solve the inequality \( 4s - 5 \geq 0 \), follow these steps:
To solve the inequality \( 4s - 5 \geq 0 \), follow these steps:
- Add 5 to both sides: \( 4s \geq 5 \)
- Then, divide both sides by 4: \( s \geq \frac{5}{4} \)
Square root function
The square root function, represented as \( f(x) = \sqrt{x} \), is a special type of function that "undoes" squaring.
The most important aspect of the square root function is that it is only defined for non-negative numbers in the real number system. This means you cannot take the square root of a negative number and expect a real result.
The most important aspect of the square root function is that it is only defined for non-negative numbers in the real number system. This means you cannot take the square root of a negative number and expect a real result.
- The symbol \( \sqrt{} \) implies finding a number which, when squared, returns the original number under the root.
- For example, \( \sqrt{9} = 3 \) because \( 3^2 = 9 \).
- In contrast, \( \sqrt{-9} \) does not result in a real number.
Interval notation
Interval notation is a concise way of expressing the set of numbers that satisfy an inequality. In mathematics, it provides an efficient way to communicate which values are included in or excluded from a solution set.
In the solution to \( f(s) = \sqrt{4s - 5} \), we determined \( s \geq \frac{5}{4} \). Translated to interval notation, this is written as \( \left[\frac{5}{4}, \infty\right) \).
In the solution to \( f(s) = \sqrt{4s - 5} \), we determined \( s \geq \frac{5}{4} \). Translated to interval notation, this is written as \( \left[\frac{5}{4}, \infty\right) \).
- The \( [ \) means "including" \( \frac{5}{4} \).
- The \( \infty \) denotes that there is no upper bound – \( s \) can be as large as any real number.
- The \( ) \) following \( \infty \) means infinity itself is not included, as it is not a real number.