Question

Given l=28 s=144 and there are total 9 terms find a

Answer 1

this is the answer of your question

Answer 2

Answer:

First term in given A.P = a = 4

Explanation:

Let a is the first term in A.P

Given,

$n^{th} term \\= last\: term (l) = 144$ ----(1)

n = 9 ----(2)

$Sum\: of\: first\: 9 \:terms \\= S_{9} = 144$----(3)

/* We know that,

$\boxed { S_{n}=\frac{n}{2}(a+l)}$ */

$144 = \frac{9}{2}(a+28)$

$\implies 144\times{\frac{2}{9}}=a+28$

$\implies 16\times 2=a+28$

$\implies 32-28 = a $

$\implies 4 = a $

Therefore,

a = 4

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