n^ th term of the series 3.8 + 6.11 + 9.14 + 12.17 + ..... will b… - Vidyadip

MCQ

${n^{th}}$ term of the series $3.8 + 6.11 + $ $9.14 + 12.17 + .....$ will be

✓
$3n(3n + 5)$
B
$3n(n + 5)$
C
$n(3n + 5)$
D
$n(n + 5)$

✓

Answer

Correct option: A.

$3n(3n + 5)$

a
(a) Given series $3\,.\,8 + 6\,.\,11 + 9\,.\,14 + 12\;.\,17 + .....$

First factors are $3, 6, 9, 12$ whose ${n^{th}}$ term is $3n$

and second factors are $8, 11, 14, 17$

${t_n} = [8 + (n - 1)3] = (3n + 5)$

Hence ${n^{th}}$ term of given series $ = 3n(3n + 5)$.

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