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## Answers

S1=a1=2(1)^2+5(1)=2+5=7

s2=2(2)^2+5(2)=8+10=18

a2=s2-s1 =18-7=11

similarly an(nth term)=sn-sn-1

sn=2n^2+5n

Sn-1=2(n-1)^2+5(n-1)

2(n^2-2n+1)+5(n-1)

2n^2-4n+2+5n-5

2n^2+n-3

nth term=2n^2-2n^2-5n-n+3

=4n+3

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S1=a1=2(1)^2+5(1)=2+5=7

s2=2(2)^2+5(2)=8+10=18

a2=s2-s1 =18-7=11

similarly an(nth term)=sn-sn-1

sn=2n^2+5n

Sn-1=2(n-1)^2+5(n-1)

2(n^2-2n+1)+5(n-1)

2n^2-4n+2+5n-5

2n^2+n-3

nth term=2n^2-2n^2-5n-n+3

=4n+3