Finding a Restricted Domain of a Composition

If [tex]$f(x)=\frac{1}{x}$[/tex] and [tex]$g(x)=x+4$[/tex], then [tex][tex]$f(x)$[/tex][/tex] is undefined when [tex]$x=$ \square[/tex] but [tex]$g(x)$[/tex] is defined for all real numbers.



Answer :

To determine when the function [tex]\( f(x) = \frac{1}{x} \)[/tex] is undefined, we need to consider the denominator of the fraction.

1. The function [tex]\( f(x) \)[/tex] is a rational function, and a rational function is undefined whenever its denominator is zero.
2. For [tex]\( f(x) = \frac{1}{x} \)[/tex], the denominator is [tex]\( x \)[/tex].
3. Setting the denominator equal to zero to find the points where the function is undefined:
[tex]\[ x = 0 \][/tex]
4. Thus, [tex]\( f(x) = \frac{1}{x} \)[/tex] is undefined when [tex]\( x = 0 \)[/tex].

Now, let’s consider the function [tex]\( g(x) = x + 4 \)[/tex]. This is a linear function of the form [tex]\( g(x) = mx + b \)[/tex] where [tex]\( m \)[/tex] and [tex]\( b \)[/tex] are constants (in this case, [tex]\( m = 1 \)[/tex] and [tex]\( b = 4 \)[/tex]).

1. Linear functions are defined for all real numbers.
2. Therefore, the function [tex]\( g(x) = x + 4 \)[/tex] does not have any restrictions on its domain.

Conclusion:

The function [tex]\( f(x) = \frac{1}{x} \)[/tex] is undefined when [tex]\( x = 0 \)[/tex], while the function [tex]\( g(x) = x + 4 \)[/tex] is defined for all real numbers. Therefore, [tex]\( f(x) \)[/tex] has a restricted domain at [tex]\( x = 0 \)[/tex].