Given that
Sn=3n^2+5n
t1 = S1
=3(1^2) + 5(1)
= 3 + 5
= 8
The sum of the first 2 terms
= 3(2^2) + 5(2)
= 12 + 10
= 22
If the first term is 8 then the second
= 22 - 8
= 14
Ther common difference which is the difference between the second and the first
= 14 - 8
= 6
tn = 8 + (n - 1)6
= 8 + 6n - 6
= 8 - 6 + 6n
= 6n + 2
Hence, the first term is 8, the common difference is 6 and the nth term tn is 6n + 2