Answer:
a. an=4n + 4
b. 56 tiles
Explanation:
a. We know that the first term of the arithmetic sequence is 8 and the second term is 12. Let's call the common difference between consecutive terms "d". Then we can use the formula for the nth term of an arithmetic sequence:
an = a1 + (n - 1)d
where an is the nth term, a1 is the first term, and d is the common difference.
Using this formula, we can find the explicit formula for the sequence:
a1 = 8
a2 = 12
d = a2 - a1 = 12 - 8 = 4
Therefore, the explicit formula for the sequence is:
an = 8 + 4(n - 1) = 4n + 4
b. We need to find the number of tiles in the 13th row, which means we need to find a13. Using the explicit formula we just found:
a13 = 4(13) + 4 = 56
Therefore, there are 56 tiles in the 13th row of the mosaic.