What are the domain, range, and asymptote of [tex]$h(x) = (0.5)^x - 9$[/tex]?

A. Domain: [tex]\{x \mid x \ \textgreater \ 9\}[/tex]; Range: [tex]\{y \mid y \text{ is a real number}\}[/tex]; Asymptote: [tex]y = 9[/tex]

B. Domain: [tex]\{x \mid x \ \textgreater \ -9\}[/tex]; Range: [tex]\{y \mid y \text{ is a real number}\}[/tex]; Asymptote: [tex]y = -9[/tex]

C. Domain: [tex]\{x \mid x \text{ is a real number}\}[/tex]; Range: [tex]\{y \mid y \ \textgreater \ 9\}[/tex]; Asymptote: [tex]y = 9[/tex]

D. Domain: [tex]\{x \mid x \text{ is a real number}\}[/tex]; Range: [tex]\{y \mid y \ \textgreater \ -9\}[/tex]; Asymptote: [tex]y = -9[/tex]



Answer :

To determine the domain, range, and asymptotes of the function [tex]\( h(x) = (0.5)^x - 9 \)[/tex], we need to analyze the behavior and properties of the function step by step.

1. Domain:
The domain of a function is the set of all possible input values (x-values) for which the function is defined. For the function [tex]\( h(x) = (0.5)^x - 9 \)[/tex], there are no restrictions on the values that [tex]\( x \)[/tex] can take. Exponential functions are always defined for all real numbers. Hence, the domain is:
[tex]\[ \{x \mid x \text{ is a real number}\} \][/tex]

2. Range:
The range of a function is the set of all possible output values (y-values).

Consider the function [tex]\( g(x) = (0.5)^x \)[/tex]. The base of the exponential function is [tex]\(0.5\)[/tex], which is a positive number less than 1. As [tex]\( x \)[/tex] becomes very large, [tex]\( (0.5)^x \)[/tex] approaches 0 but never actually reaches 0. As [tex]\( x \)[/tex] becomes very large negative, [tex]\( (0.5)^x \)[/tex] increases without bound. So, [tex]\( g(x) \)[/tex] takes positive values.

Now, subtracting 9 from [tex]\( g(x) \)[/tex]:
[tex]\[ h(x) = (0.5)^x - 9 \][/tex]
This function will shift [tex]\( g(x) \)[/tex] vertically downward by 9 units. Therefore, the minimum value of [tex]\( h(x) \)[/tex] approaches [tex]\(-9\)[/tex] when [tex]\( x \)[/tex] goes to infinity, but [tex]\( h(x) \)[/tex] will never actually reach [tex]\(-9\)[/tex]. Consequently, for very large negative [tex]\( x \)[/tex], [tex]\( h(x) \)[/tex] can take values as large as we want. Thus, the range of [tex]\( h(x) \)[/tex] is:
[tex]\[ \{y \mid y > -9\} \][/tex]

3. Asymptote:
An asymptote is a line that the graph of the function approaches but never touches or crosses. Given that [tex]\( (0.5)^x \)[/tex] approaches 0 as [tex]\( x \)[/tex] approaches [tex]\( \infty \)[/tex], [tex]\( h(x) \)[/tex] will approach [tex]\( -9 \)[/tex] but never actually reach it. Thus, the horizontal asymptote of [tex]\( h(x) \)[/tex] is:
[tex]\[ y = -9 \][/tex]

Based on this analysis, we conclude that the domain, range, and horizontal asymptote of the function [tex]\( h(x) = (0.5)^x - 9 \)[/tex] are as follows:
- Domain: [tex]\(\{x \mid x \text{ is a real number}\}\)[/tex]
- Range: [tex]\(\{y \mid y > -9\}\)[/tex]
- Asymptote: [tex]\( y = -9 \)[/tex]

Therefore, the correct choice from the given options is:
[tex]\[ \{x \mid x \text{ is a real number}\}; \{y \mid y > -9\}; y = -9 \][/tex]