Find the sum of the following arithmetic progressions:$ -26,-24,-22, \ldots $ to 36 terms.

Given:

Given A.P. is \( -26,-24,-22, \ldots \) 

To do:

We have to find the sum of the given A.P. to $36$ terms.
Solution:

Here,

\( a=-26, d=-24-(-26)=-24+26=2 \) and \( n=36 \)

We know that,

\( S_{n}=\frac{n}{2}[2 a+(n-1) d] \)
\( \therefore S_{36}=\frac{36}{2}[2 \times(-26)+(36-1) \times 2] \)
\( =18[-52+35 \times 2]=18[-52+70] \)
\( =18 \times 18=324 \) 

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Updated on: 10-Oct-2022

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