Final answer:
The function representing the length of the invasive vine after n days is
, where 18 is the original length, 0.455 is the daily growth rate, and n is the number of days since observation.
Step-by-step explanation:
To represent the growth of an invasive vine in a function, we can define f(n) as the length of the vine n days since it was first observed. Since the vine's initial length is 18 feet and it grows at a rate of 45.5% daily, the function f(n) would be:

Here, 18 is the original length of the vine in feet, 0.455 represents the 45.5% daily growth rate, and n is the number of days since the vine was first spotted. The exponential function indicates the rapid and continuous growth of the invasive species, a prime illustration of how non-native plants like kudzu can become problematic, as seen in the southeastern United States where kudzu has overpowered local vegetation.