Question Detail
In the series 3, 9, 15.. what will be the 21st term ?
- 123
- 126
- 129
- 136
Answer: Option A
Explanation:
We can judge that it is A.P.
With 6 as difference
nth term in A.P. = a+(n-1)d
a= 3, n = 21, d = 6
So, 21st term will be = 3+(20)6 = 123