If _ i = 1 ^n i = n(n + 1) 2 , then _ i = 1 ^n (3i - 2) = - Vidyadip

MCQ

If $\sum\limits_{i = 1}^n {i = \frac{{n(n + 1)}}{2}} $, then $\sum\limits_{i = 1}^n {(3i - 2) = } $

✓
$\frac{{n(3n - 1)}}{2}$
B
$\frac{{n(3n + 1)}}{2}$
C
$n(3n + 2)$
D
$\frac{{n(3n + 1)}}{4}$

✓

Answer

Correct option: A.

$\frac{{n(3n - 1)}}{2}$

a
(a) $\sum\limits_{i = 1}^n {} = 3\sum\limits_{i = 1}^n i - 2\sum\limits_{i = 1}^n 1 = 3\frac{{n\,(n + 1)}}{2} - 2n = \frac{{n\,(3n - 1)}}{2}$.

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