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Find the sums given below:
$34 + 32 + 30 + … + 10$
 Given:
$34 + 32 + 30 + … + 10$
To do:
We have to find the given sum.
Solution:
$a=34, d=32-34=-2, a_n=10$
We know that,
$a_n=l=a+(n-1)d$
$S_{n}=\frac{n}{2}[a+l]$
$a_{n}=a+(n-1) d$
$10=34+(n-1)(-2)$
$10-34=(n-1)(-2)$
$\frac{-24}{-2}=n-1$
$n-1=12$
$n=12+1$
$n=13$
Therefore,
$S_{13}=\frac{13}{2}[34+10]$
$=\frac{13}{2}(44)$
$=13 \times 22$
$=286$
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