Final answer:
The fourth term of the sequence a_n, where a_1 is 5 and each term is three times the previous term, is calculated to be 135 by recursively applying the formula three times.
Step-by-step explanation:
The question requires us to calculate the fourth term of a sequence a_n where the first term a_1 is given as 5 and the recursion formula is a_n = 3a_{n-1}. To find a_4, we will apply the recursive formula three times starting with a_1.
- a_2 = 3 × a_1 = 3 × 5 = 15
- a_3 = 3 × a_2 = 3 × 15 = 45
- a_4 = 3 × a_3 = 3 × 45 = 135
Therefore, the value of a_4 is 135.