What is the n-th term of the sequence 2, 6, 12, 20…?
- 4n - 2
- 2(3n - 1)
-
n2 + n
- n2 + 3n + 2
The correct answer is: C
Explanation
Given that 2, 6, 12, 20...? the nth term = n\(^2\) + n
check: n = 1, u1 = 2
n = 2, u2 = 4 + 2 = 6
n = 3, u3 = 9 + 3 = 12
∴ n = 4, u4 = 16 + 4 = 20
There is an explanation video available .