3, 5, 12, 55, 648, ? whats the next number in the sequence?

Find the sum of the first 30 terms of the arithmetic sequence: 7, 10, 13, 16, 19, …

In horse racing, a “trifecta” occurs when a bettor wins by selecting the first three finishers in the exact order (1 St place, 2nd place, and 3rd place). How many different trifectas are possible if there are 14 horses in a race?

Find the common ratio for the geometric sequence 2.5,5,10,20,...

Describe three ways that a sequence can be defined.