Which term of the series 4, 9, 14, 19, ... is 129?
Show answer & explanation
Correct answer: C
Explanation
Given:
Series = 4, 9, 14, 19, …
Last term = 129
By the formula:
The nth term of the AP
aₙ = a + (n − 1)d
a = 4
d = 9 − 4 = 5
129 = 4 + (n − 1) × 5
129 − 4 = (n − 1) × 5
125 = (n − 1) × 5
n − 1 = 25
n = 26th term