Chapter 2: Problem 26
Find the domain of each function. $$ h(x)-\sqrt{x-3}+\sqrt{x+4} $$
Short Answer
Expert verified
The domain of the function \( h(x) = \sqrt{x-3} + \sqrt{x+4} \) is \(x \geq 3\).
Step by step solution
01
Solving for \(x - 3\) to be greater than or equal to zero
Firstly, you need to solve for the x-values that will make the expression \(x-3\) greater than or equal to zero. The reason is that the square root of a number, which is less than zero, is not a real number. Solving the inequality \(x-3 \geq 0\), you get \(x \geq 3\). So, for the expression \(x - 3\) under the square root, x should be equal to or greater than 3 for the function to be real.
02
Solving for \(x + 4\) to be greater than or equal to zero
Similarly, for the square root of \(x + 4\) to yield a real number, \(x + 4\) should be greater than or equal to zero. Solving the inequality \(x + 4 \geq 0\), you get \(x \geq -4\). So, for the expression \(x + 4\) under the square root, x should be equal to or greater than -4 for the function to be real.
03
Determining the domain
Having solved for x in both inequalities, you can determine the domain of the function. The domain of the function will be the intersection of the solutions from both inequalities since x must satisfy both conditions for the function to be defined. The intersection of \(x \geq 3\) and \(x \geq -4\) is \(x \geq 3\). Therefore, the domain of the function \(h(x) = \sqrt{x-3} + \sqrt{x+4}\) is \(x \geq 3\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Square Root Function
The square root function, often represented as \( \sqrt{x} \), is a function that returns the non-negative square root of a number \( x \). For example, \( \sqrt{9} = 3 \), because 3 multiplied by itself equals 9.
- The square root function is only defined for non-negative numbers \( x \geq 0 \). This is because the square root of a negative number is not a real number.
- In the context of our problem, we have two expressions under the square roots: \( \sqrt{x-3} \) and \( \sqrt{x+4} \).
Inequalities
Inequalities are mathematical expressions used to compare two values, often involving symbols such as \( >, <, \geq, \) or \( \leq \). In this exercise, inequalities help us find conditions under which the square root function is defined.
- The inequality \( x - 3 \geq 0 \) simplifies to \( x \geq 3 \). This tells us that \( x \) must be 3 or greater for the square root expression \( \sqrt{x-3} \) to be a real number.
- The inequality \( x + 4 \geq 0 \) simplifies to \( x \geq -4 \). This indicates that \( x \) must be -4 or greater for \( \sqrt{x+4} \) to be real, allowing values like \( x = -4, -3, \text{etc.} \)
Real Numbers
Real numbers include all the numbers on the number line. These cover both rational numbers, like fractions and integers, and irrational numbers, like \( \sqrt{2} \) or \( \pi \).
- Real numbers are infinite and provide a complete set of values for most algebraic operations, including addition and subtraction, multiplication and division, as well as square roots.
- In our problem, the terms under the square roots need to be real numbers for \( h(x) = \sqrt{x-3} + \sqrt{x+4} \) to be defined.