Q. 55.0( 4 Votes )

If the sum to first n terms of an A.P. is , find its 25th term.

Answer :


Taking n = 1, we get




S1 = 4


a1 = 4


Taking n = 2, we get




S2 = 11


a2 = S2 – S1 = 11 – 4 = 7


Taking n = 3, we get




S3 = 21


a3 = S3 – S2 = 21 – 11 = 10


So, a = 4,


d = a2 – a1 = 7 – 4 = 3


Now, we have to find the 25th term


an = a + (n – 1)d


a25 = 4 + (25 – 1)3


a25 = 4 + 24 × 3


a25 = 4 + 72


a25 = 76


Hence, the 25th term is 76.


Rate this question :

How useful is this solution?
We strive to provide quality solutions. Please rate us to serve you better.
Related Videos
Champ Quiz | Arithmetic Progression34 mins
Champ Quiz | Arithmetic Progression30 mins
Lets Check Your Knowledge in A.P.49 mins
NCERT | Fundamental Theorem Of Arithmetic45 mins
Fundamental Theorem of Arithmetic- 143 mins
Arithmetic progression: Previous Year NTSE Questions34 mins
Quiz on Arithmetic Progression Quiz32 mins
Arithmetic Progression Tricks and QUIZ37 mins
Quiz | Group of Questions on General Term of an A.P49 mins
Get to Know About Geometric Progression41 mins
Try our Mini CourseMaster Important Topics in 7 DaysLearn from IITians, NITians, Doctors & Academic Experts
Dedicated counsellor for each student
24X7 Doubt Resolution
Daily Report Card
Detailed Performance Evaluation
view all courses