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Find \( f+g, f-g \), \( f g \), and \( \frac{f}{g} \). Determine the domain for each function \( (f+g)(x)=\sqrt{x} ; g(x)=x-9 \) What is the domain of \( f+g \) ? A. The domain of \( f+g \) is \( \} \). (Use a comma to separate answers as needed) C. The domain of \( f+g \) is \( \{0, \infty) \). (Type your answer in interval notation ) \( f+g \) is \( \varnothing \) ( \( f-g)(x)=\sqrt{x}-x+9 \) (Simplify your answer) What is the domain of \( f-g \) ? A. The domain of \( f-g \) is \( \square \). (Type your answer in interval notation.) B. The domain of \( f-g \) is \( \} \) (Use a comma to separate answers as needed) C. The domain of \( f-g \) is \( \varnothing \).

Ask by Carter O'Quinn. in the United States
Jan 25,2025

Real Tutor Solution

Tutor-Verified Answer

Answer

- **Domain of \( f+g \)**: \( [0, \infty) \) - **Domain of \( f-g \)**: \( [0, \infty) \) - **Domain of \( fg \)**: \( [0, \infty) \) - **Domain of \( \frac{f}{g} \)**: \( [0, 9) \cup (9, \infty) \)

Solution

To solve the problem, we need to find the functions \( f \) and \( g \) based on the given information and then compute \( f+g \), \( f-g \), \( fg \), and \( \frac{f}{g} \). We will also determine the domain for each function. ### Step 1: Identify \( f \) and \( g \) We know: - \( (f+g)(x) = \sqrt{x} \) - \( g(x) = x - 9 \) From the equation \( (f+g)(x) = f(x) + g(x) = \sqrt{x} \), we can express \( f(x) \) as: \[ f(x) = \sqrt{x} - g(x) = \sqrt{x} - (x - 9) = \sqrt{x} - x + 9 \] ### Step 2: Calculate \( f+g \) We already have: \[ f+g = \sqrt{x} \] ### Step 3: Calculate \( f-g \) Now, we can find \( f-g \): \[ f-g = f(x) - g(x) = (\sqrt{x} - x + 9) - (x - 9) = \sqrt{x} - x + 9 - x + 9 = \sqrt{x} - 2x + 18 \] ### Step 4: Calculate \( fg \) Next, we calculate \( fg \): \[ fg = f(x) \cdot g(x) = (\sqrt{x} - x + 9)(x - 9) \] ### Step 5: Calculate \( \frac{f}{g} \) Now, we calculate \( \frac{f}{g} \): \[ \frac{f}{g} = \frac{\sqrt{x} - x + 9}{x - 9} \] ### Step 6: Determine the domains 1. **Domain of \( f+g \)**: - Since \( f+g = \sqrt{x} \), the domain is \( x \geq 0 \). - In interval notation, the domain is \( [0, \infty) \). 2. **Domain of \( f-g \)**: - The expression \( f-g = \sqrt{x} - 2x + 18 \) requires \( \sqrt{x} \) to be defined, so \( x \geq 0 \). - Additionally, we need to ensure that \( f-g \) does not lead to any undefined expressions. Since \( \sqrt{x} \) is defined for \( x \geq 0 \), the domain remains \( [0, \infty) \). 3. **Domain of \( fg \)**: - The product \( fg \) is defined as long as both \( f \) and \( g \) are defined. Since \( g(x) = x - 9 \) is defined for all \( x \), we only need to consider \( f(x) \) which requires \( x \geq 0 \). - Thus, the domain is \( [0, \infty) \). 4. **Domain of \( \frac{f}{g} \)**: - The function \( \frac{f}{g} \) is defined as long as \( g(x) \neq 0 \). This means \( x - 9 \neq 0 \) or \( x \neq 9 \). - Therefore, the domain is \( [0, 9) \cup (9, \infty) \). ### Final Answers - The domain of \( f+g \) is \( [0, \infty) \). - The domain of \( f-g \) is \( [0, \infty) \). - The domain of \( fg \) is \( [0, \infty) \). - The domain of \( \frac{f}{g} \) is \( [0, 9) \cup (9, \infty) \). ### Summary of Domains - **Domain of \( f+g \)**: \( [0, \infty) \) - **Domain of \( f-g \)**: \( [0, \infty) \) - **Domain of \( fg \)**: \( [0, \infty) \) - **Domain of \( \frac{f}{g} \)**: \( [0, 9) \cup (9, \infty) \)

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To find \( f \) given that \( (f+g)(x)=\sqrt{x} \) and \( g(x)=x-9 \), we can express \( f(x) \) as follows: \[ f(x) = (f+g)(x) - g(x) = \sqrt{x} - (x - 9) = \sqrt{x} - x + 9 \] Now we can determine \( f-g \) as follows: \[ (f-g)(x) = f(x) - g(x) = (\sqrt{x} - x + 9) - (x - 9) = \sqrt{x} - 2x + 18 \] Next, let’s determine the domains: 1. For \( f+g \): The function \( \sqrt{x} \) is defined for \( x \geq 0 \). Thus, the domain of \( f+g \) is \( [0, \infty) \). 2. For \( f-g \): The square root function \( \sqrt{x} \) requires \( x \geq 0 \), and the linear function \( -2x + 18 \) is defined for all \( x \). Therefore, the domain of \( f-g \) is also \( [0, \infty) \). So, to summarize: **The domain of \( f+g \) is \( [0, \infty) \).** **The domain of \( f-g \) is also \( [0, \infty) \).**

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