To find the 15th term of the sequence 20, 16, 12, we first need to identify the pattern in the sequence. Observing the numbers, we see that each term decreases by 4:
- 20 – 4 = 16
- 16 – 4 = 12
From this, we can ascertain that the sequence is an arithmetic series where the first term (a) is 20, and the common difference (d) is -4.
The formula for the nth term of an arithmetic sequence is:
T(n) = a + (n – 1) * d
To find the 15th term (n = 15):
T(15) = 20 + (15 – 1) * (-4)
T(15) = 20 + 14 * (-4)
T(15) = 20 – 56
T(15) = -36
Therefore, the 15th term of the sequence is -36.