Final answer:
The population for the 8th, 12th, and 40th year can be calculated using the explicit formula a, = 1000(2)^k. For the 8th year, the population would be 256,000. For the 12th year, the population would be 4,096,000. And for the 40th year, the population would be 1,099,511,627,776,000.
Step-by-step explanation:
To find the population for the 8th, 12th, and 40th year, we can substitute the corresponding values of k into the explicit formula. The explicit formula given is: an= 1000(2)k.
For the 8th year (k = 8), we have: a8 = 1000(2)8 = 1000(256) = 256,000.
For the 12th year (k = 12), we have: a12 = 1000(2)12 = 1000(4096) = 4,096,000.
For the 40th year (k = 40), we have: a40 = 1000(2)40 = 1000(1,099,511,627,776) = 1,099,511,627,776,000.