Answer:
1. The explicit formula for the arithmetic sequence is aₙ = 6n - 14.
2. an = 5n + 1
3. The answer 'No.' means that there is no solution to the Equilateral Triangle Problem using the numbers 4, 5, and 9 at the vertices. It implies that it is not possible to arrange these numbers in such a way that forms an equilateral triangle.
Explanation: