Arithmetic progression for Tn,=6n+ 5, so find sn=_
Akanxa11:
sorry Tn= 6n +5
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put n= 1 , 2 .... ull get the terms
then u can know a and d then put it in the formula , n/2(2a+ (n-1)d)
Answer is ------ n/2(18+6n)
11 , 17 , 23 , 29, ...
a=11
d=6
Sn=n/2(2a+(n-1)d)
=n/2(16+6n)
= n/2 ×2 (8 +3n)
2 comman
= n(8+3n)
=3n2+8n
hii
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