Questions: The functions f and g are defined as f(x)=x-5, g(x)=√(x+6). a) Find the domain of f, g, f+g, f-g, fg, ff, f/g, and g/f. b) Find (f+g)(x), (f-g)(x), (fg)(x), (f)(x),(f/g)(x), and (g/f)(x). a) The domain of f is (-∞, ∞). (Type your answer in interval notation.) The domain of g is . (Type your answer in interval notation.)

The functions f and g are defined as f(x)=x-5, g(x)=√(x+6).
a) Find the domain of f, g, f+g, f-g, fg, ff, f/g, and g/f.
b) Find (f+g)(x), (f-g)(x), (fg)(x), (f)(x),(f/g)(x), and (g/f)(x).
a) The domain of f is (-∞, ∞).
(Type your answer in interval notation.)
The domain of g is .
(Type your answer in interval notation.)
Transcript text: The functions $f$ and $g$ are defined as $f(x)=x-5, g(x)=\sqrt{x+6}$. a) Find the domain of $f, g, f+g, f-g, f g, f f, \frac{f}{g}$, and $\frac{g}{f}$. b) Find $(f+g)(x)$, $(f-g)(x)$, $(f g)(x)$, $(f)(x),\left(\frac{f}{g}\right)(x)$, and $\left(\frac{g}{f}\right)(x)$. a) The domain of $f$ is $(-\infty, \infty)$. (Type your answer in interval notation.) The domain of $g$ is $\square$ . (Type your answer in interval notation.)
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Solution

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Solution Steps

To solve the given problem, we need to determine the domains of the functions \( f \) and \( g \), as well as their combinations. Then, we will find the expressions for the combined functions.

Part (a)
  1. Domain of \( f(x) = x - 5 \): Since \( f(x) \) is a linear function, its domain is all real numbers, \( (-\infty, \infty) \).
  2. Domain of \( g(x) = \sqrt{x + 6} \): The expression inside the square root must be non-negative, so \( x + 6 \geq 0 \). Therefore, the domain is \( [-6, \infty) \).

For the combined functions:

  • \( f + g \): The domain is the intersection of the domains of \( f \) and \( g \), which is \( [-6, \infty) \).
  • \( f - g \): The domain is the same as \( f + g \), which is \( [-6, \infty) \).
  • \( f \cdot g \): The domain is the same as \( f + g \), which is \( [-6, \infty) \).
  • \( \frac{f}{g} \): The domain is \( [-6, \infty) \) excluding points where \( g(x) = 0 \). Since \( g(x) = \sqrt{x + 6} \), \( g(x) = 0 \) when \( x = -6 \). Thus, the domain is \( (-6, \infty) \).
  • \( \frac{g}{f} \): The domain is \( [-6, \infty) \) excluding points where \( f(x) = 0 \). Since \( f(x) = x - 5 \), \( f(x) = 0 \) when \( x = 5 \). Thus, the domain is \( [-6, 5) \cup (5, \infty) \).
Part (b)
  1. \( (f + g)(x) \): This is \( f(x) + g(x) \).
  2. \( (f - g)(x) \): This is \( f(x) - g(x) \).
  3. \( (f \cdot g)(x) \): This is \( f(x) \cdot g(x) \).
  4. \( \left(\frac{f}{g}\right)(x) \): This is \( \frac{f(x)}{g(x)} \).
  5. \( \left(\frac{g}{f}\right)(x) \): This is \( \frac{g(x)}{f(x)} \).
Step 1: Determine the Domain of \( f(x) \)

The function \( f(x) = x - 5 \) is a linear function. Linear functions are defined for all real numbers.

\[ \text{Domain of } f: (-\infty, \infty) \]

Step 2: Determine the Domain of \( g(x) \)

The function \( g(x) = \sqrt{x + 6} \) is defined when the expression inside the square root is non-negative.

\[ x + 6 \geq 0 \implies x \geq -6 \]

\[ \text{Domain of } g: [-6, \infty) \]

Step 3: Determine the Domain of Combined Functions
  • \( f + g \): The domain is the intersection of the domains of \( f \) and \( g \).

\[ \text{Domain of } f + g: [-6, \infty) \]

  • \( f - g \): The domain is the same as \( f + g \).

\[ \text{Domain of } f - g: [-6, \infty) \]

  • \( f \cdot g \): The domain is the same as \( f + g \).

\[ \text{Domain of } f \cdot g: [-6, \infty) \]

  • \( \frac{f}{g} \): The domain is \( [-6, \infty) \) excluding points where \( g(x) = 0 \). Since \( g(x) = \sqrt{x + 6} \), \( g(x) = 0 \) when \( x = -6 \).

\[ \text{Domain of } \frac{f}{g}: (-6, \infty) \]

  • \( \frac{g}{f} \): The domain is \( [-6, \infty) \) excluding points where \( f(x) = 0 \). Since \( f(x) = x - 5 \), \( f(x) = 0 \) when \( x = 5 \).

\[ \text{Domain of } \frac{g}{f}: [-6, 5) \cup (5, \infty) \]

Step 4: Find the Expressions for Combined Functions
  • \( (f + g)(x) \):

\[ (f + g)(x) = f(x) + g(x) = x - 5 + \sqrt{x + 6} \]

  • \( (f - g)(x) \):

\[ (f - g)(x) = f(x) - g(x) = x - 5 - \sqrt{x + 6} \]

  • \( (f \cdot g)(x) \):

\[ (f \cdot g)(x) = f(x) \cdot g(x) = (x - 5) \sqrt{x + 6} \]

  • \( \left(\frac{f}{g}\right)(x) \):

\[ \left(\frac{f}{g}\right)(x) = \frac{f(x)}{g(x)} = \frac{x - 5}{\sqrt{x + 6}} \]

  • \( \left(\frac{g}{f}\right)(x) \):

\[ \left(\frac{g}{f}\right)(x) = \frac{g(x)}{f(x)} = \frac{\sqrt{x + 6}}{x - 5} \]

Final Answer

\[ \boxed{[-6, \infty)} \]

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