Sara Solomon
2022-10-01
Answered

Find the sum of the arithmetic sequence having the data given ${a}_{1}=5$, d = -2, n = 12

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blikath3

Answered 2022-10-02
Author has **7** answers

The sum of n terms of arithmetic sequence is found using formula:

${S}_{n}=\frac{n}{2}[2a+(n-1)d]$

${S}_{n}=\frac{12}{2}[2\times 5+(12-1)\times -2]$

$=6[10+\left(11\right)\times -2]$

$=6[10-22]$

$=6\times -12$

${S}_{12}=-72$

${S}_{n}=\frac{n}{2}[2a+(n-1)d]$

${S}_{n}=\frac{12}{2}[2\times 5+(12-1)\times -2]$

$=6[10+\left(11\right)\times -2]$

$=6[10-22]$

$=6\times -12$

${S}_{12}=-72$

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