Final answer:
To determine the nth term of an arithmetic sequence with a first term of 18 and a second term of 17.91, find the common difference and use the arithmetic sequence formula.
Step-by-step explanation:
The first term of an arithmetic sequence is given as 18, and the second term is 17.91. To determine the nth term of the sequence, we must first find the common difference of the sequence. The common difference (d) is the difference between any two successive terms, which can be calculated by subtracting the first term from the second term:
d = 17.91 - 18 = -0.09
Now that we have the common difference, the nth term of an arithmetic sequence can be determined using the formula:
an = a1 + (n - 1)d
Substituting the given terms into the formula gives us:
an = 18 + (n - 1)(-0.09)
Simplifying the equation, we arrive at the general expression for the nth term:
an = 18 - 0.09(n - 1)