Find Sn if an=3+2n

1.	Find Sn if an=3+2n
Answer» Given, an\xa0= 3 + 2na1\xa0= 3 + 2{tex}\\times{/tex}1 = 5a2\xa0= 3 + 2{tex}\\times{/tex}2 = 7a3\xa0= 3 + 2{tex}\\times{/tex}3 = 9Thus the series is 5, 7, 9,......in which a = 5 and d = 7 - 5 = 2{tex}\\therefore \\quad S _ { n } = \\frac { n } { 2 } ( 2 a + ( n - 1 ) d ){/tex}Sn\xa0=\xa0{tex}\\frac n2{/tex}[2(5) + (n - 1)2]Sn\xa0=\xa0{tex}\\frac n2{/tex}[10\xa0+ 2n - 2]Sn\xa0=\xa0{tex}\\frac n2{/tex}[8\xa0+ 2n]Sn\xa0= 4n + n2\xa0

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