Final answer:
The formula for the nth term of the arithmetic sequence 15, 11, 7, 3,... is , with being the common difference.
Step-by-step explanation:
To determine the nth term () for the arithmetic sequence 15, 11, 7, 3,..., we first need to find the common difference (). The difference between successive terms is 11 - 15 = -4, so the common difference () is -4. The nth term of an arithmetic sequence can be found using the formula , where is the first term and is the common difference. For this sequence, and .
Substituting these values into the formula:
So the correct formula for the nth term of this arithmetic sequence is -4n + 19.