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In an AP:
Given $l = 28, S = 144$, and there are total 9 terms. Find $a$.
Given:
To do:
We have to find $a$.
Solution:
$a_n=l=28$
We know that,
$\mathrm{S}_{n}=\frac{n}{2}[a+l]$
$S_n=\frac{9}{2}[a+28]$
$144(2)=9(a+28)$
$16(2)=a+28$
$a=32-28$
$a=4$
Therefore, $a=4$.
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