Question

In an AP, if Sn = n(4n+1), find the AP

Answer 1

Given ,
Sn =n ( 4n + 1 )
=4n^2 + n

we know that,
Tn = Sn - S(n-1)
=4n^2+n -4 (n-1)^2 - (n-1)
=4 (n^2-n^2+2n-1)+(n-n+1)
=8n - 4 + 1
= 8n -3

hence ,
Tn = 8n -3
T1 =8 (1)-3 =5
T2= 8 (2)-3 =13
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so, AP is 5, 13 , 21 ,...

Hope that it is helpful

please mark as BRAINLIEST please

Answer 2

4n2+n
a1=s1
s1=5
s2-s1=a2
18-5=a2
a2=13