To represent the geometric sequence 6, 18, 54, ..., we need to identify the first term and the common ratio.
- The first term \( a \) is 6.
- The common ratio \( r \) can be found by dividing the second term by the first term: \( \frac{18}{6} = 3 \).
The formula for the \( n \)-th term of a geometric sequence can be described by:
\[ a_n = a \cdot r^{n-1} \]
In this case, we can express the function as:
\[ f(x) = 6 \cdot 3^{x-1} \]
where \( x \) corresponds to the term number (1 for the first term, 2 for the second term, etc.).
So, the correct representation from the options provided is:
f(x) = 6(3)^(x−1)