If [tex]$f(x) = (x+1)^{-1}$[/tex] and [tex]$g(x) = x-2$[/tex], what is the domain of [tex]$f(x) \div g(x)$[/tex]?

A. all values of [tex]$x$[/tex]

B. [tex]$(-\infty, -1) \cup (-1, 2) \cup (2, \infty)$[/tex]

C. [tex]$(-\infty, 2) \cup (2, \infty)$[/tex]

D. [tex]$(-\infty, -1] \cup [2, \infty)$[/tex]



Answer :

To determine the domain of the function [tex]\( \frac{f(x)}{g(x)} \)[/tex] where [tex]\( f(x) = \frac{1}{x+1} \)[/tex] and [tex]\( g(x) = x-2 \)[/tex], we need to consider where both functions are well-defined and where the overall expression is defined.

1. Identify the domain of [tex]\( f(x) \)[/tex]:
[tex]\( f(x) = \frac{1}{x+1} \)[/tex]. This function is undefined where the denominator is zero:
[tex]\[ x + 1 = 0 \implies x = -1 \][/tex]
Therefore, [tex]\( f(x) \)[/tex] is undefined at [tex]\( x = -1 \)[/tex]. So the domain of [tex]\( f(x) \)[/tex] is all real numbers except [tex]\( x = -1 \)[/tex]:
[tex]\[ \text{Domain of } f(x) = \{ x \in \mathbb{R} : x \neq -1 \} \][/tex]

2. Identify the domain of [tex]\( g(x) \)[/tex]:
[tex]\( g(x) = x - 2 \)[/tex]. This is a linear function and it is defined for all real numbers:
[tex]\[ \text{Domain of } g(x) = \mathbb{R} \][/tex]

3. Identify where [tex]\( g(x) = 0 \)[/tex]:
[tex]\[ x - 2 = 0 \implies x = 2 \][/tex]
For the function [tex]\( \frac{f(x)}{g(x)} = \frac{\frac{1}{x+1}}{x-2} = \frac{1}{(x+1)(x-2)} \)[/tex], it will be undefined not only where [tex]\( f(x) \)[/tex] or [tex]\( g(x) \)[/tex] are undefined, but also where [tex]\( g(x) = 0 \)[/tex].

4. Combine the constraints:
We need [tex]\( x \neq -1 \)[/tex] and [tex]\( x \neq 2 \)[/tex]. So, combining these, the domain of [tex]\( \frac{f(x)}{g(x)} \)[/tex] is:
[tex]\[ \{ x \in \mathbb{R} : x \neq -1 \text{ and } x \neq 2 \} \][/tex]

In interval notation, this is expressed as:
[tex]\[ (-\infty, -1) \cup (-1, 2) \cup (2, \infty) \][/tex]

Therefore, the correct answer is:
[tex]\[ \boxed{B. (-\infty, -1), (-1, 2), \text{ and } (2, \infty)} \][/tex]