Question

find the nth term of an AP sum of whose first n term is 3n^2+2n

Answer 1

S1 = 3×1 + 4×1 = 7.

S2 = 3×4 + 4×2 = 12 + 8 = 20.

Therefore First term a1 = 7 &  Second term a2 = 20 - 7 = 13 and d = 13 - 7 = 6.

an = a+(n-1)d  = 7+(n-1)6 = 7+6n-6 = 6n+1

So, nth term is 6n+1

Answer 2

Here is your solution

Given as 

sn​=3n^2+2n 

To find out we need to find first term and Common difference 

Let n= 1

We got the first term a = 5

Now also put n=2 

Since it's the sum of 2 term =14

2nd term = S2 - a 
= 14 - 5 
= 9 

Now we have 
a1 = 5 and a2 = 9 

Now d = a2- a1 
d = 9 - 5 = 4 

n term ​=a+(n-1)d
n term=5+(n-1)4
n term=5+4n-4
n term=1+4n

hope it helps you