Math, asked by LuvNoor111, 1 year ago

The sum of first n term os an AP is given by Sn=3n^2+2n. Determine the AP and its 15th term

Answers

Answered by Disciple
0
the answer that I solved is using substitution method
Attachments:

LuvNoor111: the coming answer is 5,11,17,____,89
Disciple: I dont think it would be so big .. are you telling about the sum of 15 numbers in AP ??
LuvNoor111: yes
Disciple: okay my answer was for the 15th term in AP
Answered by SmãrtyMohït
26
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 =16

2nd term = S2 - a 
= 16- 5
= 11

Now we have 
a1 = 5 and a2 = 11

Now d = a2- a1 
d = 11- 5 = 6

Now 16th term 

15th term ​=a+14d=5+14(6)=89

hope it helps you
Similar questions