The sum of the first n terms of the A.P. -2, | vedclass

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Question

(C) The given $A.P.$ is $-2, 1, 4, 7, \ldots$Here,the first term $a = -2$.The common difference $d = 1 - (-2) = 1 + 2 = 3$.The sum of the first $n$ te

Vedclass · Accepted Answer

$\frac{n(3n-7)}{2}$

Vedclass · Answer

(C) The given $A.P.$ is $-2, 1, 4, 7, \ldots$Here,the first term $a = -2$.The common difference $d = 1 - (-2) = 1 + 2 = 3$.The sum of the first $n$ terms of an $A.P.$ is given by the formula $S_n = \frac{n}{2}[2a + (n-1)d]$.Substituting the values of $a$ and $d$ into the formula:$S_n = \frac{n}{2}[2(-2) + (n-1)3]$$S_n = \frac{n}{2}[-4 + 3n - 3]$$S_n = \frac{n(3n - 7)}{2}$.

The sum of the first $n$ terms of the $A.P.$ $-2, 1, 4, 7, \ldots$ is:

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