Question

In an AP the sum of first n terms is 3n^2/2 + 13n/2
Find its 25th term

Answer 1

Answer:25th term=80

Step-by-step explanation:

n term sum = 3n²/2 + 13n/2

as we know that nth term = (Sum of nth term ) -( sum of (n-1)th term

•METHOD 1

so 25th term=(sum of 25 terms) - ( sum of 24 terms)

=(3×(25)²/2+(13×25)/2)-( 3×(24)²/2 + (13×24)/2)

= 1100 - 1020

= 80

25th term=80

•METHOD 2

1st term = 8

sum of 2 terms = 19

2nd term = 19 - 8= 11

so. difference = 11- 8 = 3

25th term = (8 + (25 -1)×3) = 80

25th term=8

Hope it is helpful for u....

If yes then plz mark it as brainliest....

Pls it's a request to u dear....

Answer 2

plz refer to this attachment