If [tex]f(x)=\frac{x-3}{x}[/tex] and [tex]g(x)=5x-4[/tex], what is the domain of [tex](f \circ g)(x)[/tex]?

A. [tex]\{x \mid x \neq 0\}[/tex]

B. [tex]\left\{x \left\lvert\, x \neq \frac{1}{3}\right.\right\}[/tex]

C. [tex]\left\{x \left\lvert\, x \neq \frac{4}{5}\right.\right\}[/tex]

D. [tex]\{x \mid x \neq 3\}[/tex]



Answer :

Sure, let's find the domain of [tex]\((f \circ g)(x)\)[/tex] for the functions [tex]\(f(x)=\frac{x-3}{x}\)[/tex] and [tex]\(g(x)=5x-4\)[/tex].

1. Understand the functions:
- [tex]\( f(x) = \frac{x - 3}{x} \)[/tex]
- [tex]\( g(x) = 5x - 4 \)[/tex]

2. Composite function [tex]\((f \circ g)(x)\)[/tex]:
To form [tex]\((f \circ g)(x)\)[/tex], we need to compute [tex]\( f(g(x)) \)[/tex].
- First, compute [tex]\( g(x) \)[/tex]:
[tex]\[ g(x) = 5x - 4 \][/tex]
- Next, substitute [tex]\( g(x) \)[/tex] into [tex]\( f \)[/tex]:
[tex]\[ f(g(x)) = f(5x - 4) = \frac{(5x - 4) - 3}{5x - 4} = \frac{5x - 7}{5x - 4} \][/tex]

3. Determine the domain of [tex]\( f(g(x)) \)[/tex]:
- For [tex]\( f(g(x)) \)[/tex] to be defined, the denominator must not be zero.
- The denominator of [tex]\( f(g(x)) \)[/tex] is [tex]\( 5x - 4 \)[/tex].

4. Set the denominator not equal to zero:
[tex]\[ 5x - 4 \neq 0 \][/tex]
[tex]\[ 5x \neq 4 \][/tex]
[tex]\[ x \neq \frac{4}{5} \][/tex]

The domain of [tex]\((f \circ g)(x)\)[/tex] is all real numbers [tex]\( x \)[/tex] except [tex]\( \frac{4}{5} \)[/tex].

Therefore, the answer is:
[tex]\[ \left\{x \left\lvert\, x \neq \frac{4}{5}\right.\right\} \][/tex]