What are the domain and range of [tex]\( f(x) = \left(\frac{1}{5}\right)^x \)[/tex] ?

A. The domain is all real numbers. The range is all real numbers.
B. The domain is all real numbers. The range is all real numbers greater than zero.
C. The domain is all real numbers greater than zero. The range is all real numbers.
D. The domain is all real numbers greater than zero. The range is all real numbers greater than zero.



Answer :

To determine the domain and range of the function [tex]\( f(x) = \left( \frac{1}{5} \right)^x \)[/tex], let's break down the problem step by step.

### Domain

The domain of a function refers to all possible input values (typically [tex]\( x \)[/tex] values) for which the function is defined. For the function [tex]\( f(x) = \left( \frac{1}{5} \right)^x \)[/tex], note the following:

1. Exponential functions of the form [tex]\( a^x \)[/tex] where [tex]\( a > 0 \)[/tex] are defined for all real numbers [tex]\( x \)[/tex].

There are no restrictions on [tex]\( x \)[/tex] for the function [tex]\( \left( \frac{1}{5} \right)^x \)[/tex]. This means that the domain of [tex]\( f(x) \)[/tex] is all real numbers.

So, the domain is: all real numbers.

### Range

The range of a function refers to all possible output values (typically [tex]\( y \)[/tex] values) that the function can take.

For [tex]\( f(x) = \left( \frac{1}{5} \right)^x \)[/tex], we need to determine the behavior of the function as [tex]\( x \)[/tex] takes on various real numbers:

1. If [tex]\( x \)[/tex] is very large and positive, [tex]\( \left( \frac{1}{5} \right)^x \)[/tex] will approach 0, but it will never be exactly 0.
2. If [tex]\( x \)[/tex] is very large and negative, [tex]\( \left( \frac{1}{5} \right)^x \)[/tex] will grow very large, because raising [tex]\( \frac{1}{5} \)[/tex] to a large negative power is equivalent to raising 5 to a large positive power.

Thus, the function will yield positive values regardless of the input [tex]\( x \)[/tex], but it will never be zero or negative.

So the range is: all real numbers greater than zero.

### Conclusion

Combining our findings, the correct statements about the domain and range of [tex]\( f(x) = \left( \frac{1}{5} \right)^x \)[/tex] are:

- The domain is all real numbers.
- The range is all real numbers greater than zero.

Therefore, the correct answer is:

The domain is all real numbers. The range is all real numbers greater than zero.