For the two functions \( f(x)=9+\frac{7}{x} \) and \( g(x)=\frac{7}{x} \), find each of the needed functions and determine their domains. (For the domains, give your answers as intervals in the form (*,*). Use the symbol \( \infty 0 \) for infinity, \( U \) for combining intervals, and an appropriate type of parenthesis " \( \left.\left("^{\prime \prime}\right)^{\prime}\right)^{\prime}, "\left["^{n},\right]^{\prime} \) " depending on whether the interval is open or closed. Enter \( \varnothing \) if the interval is empty. Express numbers in exact form. Use symbolic notation and fractions where needed.) \[ (f+g)(x)= \] \( \square \) the domain of \( (f+g)(x) \) : \( \square \) \[ (f-g)(x)= \] \( \square \) the domain of \( (f-g)(x) \) : \( \square \) \[ (f \cdot g)(x)= \] \( \square \) the domain of \( (f, g)(x) \) : \( \square \)
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To find the functions and their respective domains, let's first compute \( (f+g)(x) \), \( (f-g)(x) \), and \( (f \cdot g)(x) \). 1. **Sum of functions:** \[ (f+g)(x) = f(x) + g(x) = \left(9 + \frac{7}{x}\right) + \frac{7}{x} = 9 + \frac{14}{x} \] The domain of \( (f+g)(x) \) excludes \( x=0 \), so: Domain of \( (f+g)(x) \): \( (-\infty, 0) \cup (0, \infty) \) 2. **Difference of functions:** \[ (f-g)(x) = f(x) - g(x) = \left(9 + \frac{7}{x}\right) - \frac{7}{x} = 9 \] This constant function is defined for all \( x \neq 0 \): Domain of \( (f-g)(x) \): \( (-\infty, 0) \cup (0, \infty) \) 3. **Product of functions:** \[ (f \cdot g)(x) = f(x) \cdot g(x) = \left(9 + \frac{7}{x}\right) \cdot \frac{7}{x} = \frac{63}{x} + \frac{49}{x^2} \] The domain also excludes \( x=0 \): Domain of \( (f \cdot g)(x) \): \( (-\infty, 0) \cup (0, \infty) \) So to summarize: \[ (f+g)(x)= 9 + \frac{14}{x} \] the domain of \( (f+g)(x) \) : \( (-\infty, 0) \cup (0, \infty) \) \[ (f-g)(x)= 9 \] the domain of \( (f-g)(x) \) : \( (-\infty, 0) \cup (0, \infty) \) \[ (f \cdot g)(x)= \frac{63}{x} + \frac{49}{x^2} \] the domain of \( (f \cdot g)(x) \) : \( (-\infty, 0) \cup (0, \infty) \)