Find the sum of the first $15$ terms of the following sequences having $n$ th term as
$b_{n} = 5 + 2 n$

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Solution

Formula,

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

Given,

$a_{n} = 5 + 2 n$

$a_{1} = 5 + 2 (1) = 7$

$l = a_{15} = 5 + 2 (15) = 35$

$S_{15} = \frac{15}{2} (7 + 35)$

$∴ S_{15} = 315$

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Find the sum of the first 15 terms of the following sequences having nth term asbn=5+2n

Formula,Sn=n2(a+l)Given,an=5+2na1=5+2(1)=7l=a15=5+2(15)=35S15=152(7+35)∴S15=315

Find the sum of the first $15$ terms of the following sequences having $n$ th term as
$b_{n} = 5 + 2 n$

Formula,

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

Given,

$a_{n} = 5 + 2 n$

$a_{1} = 5 + 2 (1) = 7$

$l = a_{15} = 5 + 2 (15) = 35$

$S_{15} = \frac{15}{2} (7 + 35)$

$∴ S_{15} = 315$