Question 8

Which of the following formats should be used for the domain of the function: [tex]f(x)=\frac{x-1}{x^2-2x-15}[/tex]?

A. [tex]x \neq M[/tex]
B. [tex]x \geq M[/tex]
C. [tex]x \leq M[/tex]
D. All Real Numbers

Based on the above choice, fill in the correct box below. Leave the others blank.

If you need to list several values, separate them with a comma. If you selected "All Real Numbers," leave the boxes below blank.

[tex]
\begin{array}{l}
x \neq \square \\
x \geq \square \\
x \leq \square
\end{array}
[/tex]



Answer :

To determine the domain of the function [tex]\( f(x) = \frac{x-1}{x^2 - 2x - 15} \)[/tex], we need to identify the values of [tex]\( x \)[/tex] that make the denominator zero, as the function is undefined at these points. This requires solving the following equation:

[tex]\[ x^2 - 2x - 15 = 0 \][/tex]

The roots of this quadratic equation, which are the values of [tex]\( x \)[/tex] making the denominator zero, are [tex]\(\boxed{5.0}\)[/tex] and [tex]\(\boxed{-3.0}\)[/tex].

These roots show the points where the function [tex]\( f(x) \)[/tex] is undefined. Therefore, the domain of [tex]\( f(x) \)[/tex] includes all real numbers except for these values. We express this by saying [tex]\( x \neq 5 \)[/tex] and [tex]\( x \neq -3 \)[/tex].

Thus, the correct format to use is:
[tex]\[ x \neq M \][/tex]

The values that make the function undefined, and hence should be excluded from the domain, are [tex]\(5\)[/tex] and [tex]\(-3\)[/tex]. These should be filled into the respective blanks in the provided choice:

[tex]\[ \begin{array}{l} x \neq 5, -3 \\ x \geq \\ x \leq \end{array} \][/tex]

Therefore, the filled boxes should look like this:
[tex]\[ x \neq 5, -3 \][/tex]

Confirming this, ensure that the other boxes are left blank. The domain of the function [tex]\( f(x) \)[/tex] is all real numbers except [tex]\( x = 5 \)[/tex] and [tex]\( x = -3 \)[/tex].