For the functions \( f(x)=6-x^{2} \) and \( g(x)=x^{2}+4 x-32 \), find \( f+g, f-g \), \( g \), and \( \frac{f}{g} \). Determine the domain for each function. What is the domain of \( \frac{1}{g} \) ? Select the correct choice below and, if necessary, fill in the answer box to complete your choice. A. The domain of \( \frac{f}{g} \) is \( \{ \). \( \} \). (Use a comma to separate answers as needed.) B. The domain of \( \frac{f}{g} \) is (Type your answer in interval notation.) C. The domain of \( \frac{f}{g} \) is \( \varnothing \).
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The Deep Dive
To find \( f + g \) and \( f - g \): 1. **Sum \( f + g \)**: \[ f + g = (6 - x^2) + (x^2 + 4x - 32) = 6 - x^2 + x^2 + 4x - 32 = 4x - 26 \] 2. **Difference \( f - g \)**: \[ f - g = (6 - x^2) - (x^2 + 4x - 32) = 6 - x^2 - x^2 - 4x + 32 = -2x^2 - 4x + 38 \] 3. **Function \( g \)**: \[ g(x) = x^2 + 4x - 32 \] 4. **Ratio \( \frac{f}{g} \)**: \[ \frac{f}{g} = \frac{6 - x^2}{x^2 + 4x - 32} \] Now determining the domains: - **Domain of \( f(x) \) and \( g(x) \)**: Both are polynomial functions, which means they are defined for all real numbers. Hence, the domain of both functions is \( (-\infty, \infty) \). - **Domain of \( \frac{f}{g} \)**: The ratio \( \frac{f}{g} \) is undefined when \( g(x) = 0 \). We can find when this occurs by solving: \[ x^2 + 4x - 32 = 0 \] Using the quadratic formula \( x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \): \[ x = \frac{-4 \pm \sqrt{(4)^2 - 4 \cdot 1 \cdot (-32)}}{2 \cdot 1} = \frac{-4 \pm \sqrt{16 + 128}}{2} = \frac{-4 \pm 12}{2} \] This gives solutions \( x = 4 \) and \( x = -8 \). Thus, the domain of \( \frac{f}{g} \) is \( (-\infty, -8) \cup (-8, 4) \cup (4, \infty) \). - **Domain of \( \frac{1}{g} \)**: Similar to the reasoning above, \( \frac{1}{g} \) is also undefined where \( g(x) = 0 \), so the domain is the same as for \( \frac{f}{g} \): \( (-\infty, -8) \cup (-8, 4) \cup (4, \infty) \). **Final Answer**: B. The domain of \( \frac{f}{g} \) is \((- \infty, -8) \cup (-8, 4) \cup (4, \infty)\).