Question

If l = 28 , S = 144 and there are total 9 terms then find a

Answer 1

Hey Mate !
~~~~~~~~~

Here is your answer :

===============================

Given,

l = 28

S = 144

n = 9

Sn = n/2 (a+l )

144 = 9/2 ( a + 28)

a + 28 = 144 × 2/9

a + 28 = 32

a = 32 - 28

a = 4


HOPE THIS HELPS U...

Answer 2

hey!

last term is given as 28 ( l )

sum of 9 terms ( as AP contain 9 term ) = 144

•Let a be first term

$sn = \frac{n}{2} (a + l) \\ s9 = \frac{9}{2} (a + 28)$



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


$288 = 9a + 252$


$288 - 252 = 9a$

$36 = 9a$


$\frac{36}{9} = a$

$a = 4$