Select the correct answer.

Which function defines [tex](f-g)(x)[/tex]?
[tex]\[
\begin{array}{l}
f(x) = \sqrt{\frac{x}{8}} + 11 \\
g(x) = 5 + \frac{2}{x}
\end{array}
\][/tex]

A. [tex](f-g)(x) = \sqrt{\frac{x}{8}} + \frac{2}{x} - 6[/tex]

B. [tex](f-g)(x) = \sqrt{\frac{x}{8}} - \frac{2}{x} + 6[/tex]

C. [tex](f-g)(x) = \sqrt{\frac{x}{8} - \frac{2}{x}} + 16[/tex]

D. [tex](f-g)(x) = \sqrt{\frac{x}{8}} + \frac{2}{x} - 16[/tex]



Answer :

To determine which function correctly defines [tex]\((f-g)(x)\)[/tex], we need to find the difference between the functions [tex]\( f(x) \)[/tex] and [tex]\( g(x) \)[/tex].

Given:
[tex]\[ f(x) = \sqrt{\frac{x}{8}} + 11 \][/tex]
[tex]\[ g(x) = 5 + \frac{2}{x} \][/tex]

We compute [tex]\((f-g)(x)\)[/tex] by subtracting [tex]\(g(x)\)[/tex] from [tex]\(f(x)\)[/tex]:

[tex]\[ (f-g)(x) = f(x) - g(x) \][/tex]

Substitute the expressions for [tex]\(f(x)\)[/tex] and [tex]\(g(x)\)[/tex]:

[tex]\[ (f-g)(x) = \left( \sqrt{\frac{x}{8}} + 11 \right) - \left( 5 + \frac{2}{x} \right) \][/tex]

Simplify the expression:

[tex]\[ (f-g)(x) = \sqrt{\frac{x}{8}} + 11 - 5 - \frac{2}{x} \][/tex]

Combine the constant terms:

[tex]\[ (f-g)(x) = \sqrt{\frac{x}{8}} + 6 - \frac{2}{x} \][/tex]

Now we compare this simplified form of [tex]\( (f-g)(x) \)[/tex] with the given choices:

A. [tex]\( (f-g)(x) = \sqrt{\frac{x}{8}} + \frac{2}{x} - 6 \)[/tex]

B. [tex]\( (f-g)(x) = \sqrt{\frac{x}{8}} - \frac{2}{x} + 6 \)[/tex]

C. [tex]\( (f-g)(x) = \sqrt{\frac{x}{8} - \frac{2}{x}} + 16 \)[/tex]

D. [tex]\( (f-g)(x) = \sqrt{\frac{x}{8}} + \frac{2}{x} - 16 \)[/tex]

The correct expression must match our simplified form [tex]\( \sqrt{\frac{x}{8}} + 6 - \frac{2}{x} \)[/tex].

Comparing this form with the choices, we see:

- Choice B: [tex]\( \sqrt{\frac{x}{8}} - \frac{2}{x} + 6 \)[/tex] matches exactly.

Thus, the correct choice is:

B. [tex]\( (f-g)(x) = \sqrt{\frac{x}{8}} - \frac{2}{x} + 6 \)[/tex].