Use app×
Join Bloom Tuition
One on One Online Tuition
JEE MAIN 2025 Foundation Course
NEET 2025 Foundation Course
CLASS 12 FOUNDATION COURSE
CLASS 10 FOUNDATION COURSE
CLASS 9 FOUNDATION COURSE
CLASS 8 FOUNDATION COURSE
0 votes
126 views
in Arithmetic Progression by (24.8k points)
closed by

If the sum of n terms of an A.P., is 3n2 + 5n which of its terms is 164? 

A. 26th 

B. 27th 

C. 28th 

D. none of these

1 Answer

+1 vote
by (27.0k points)
selected by
 
Best answer

Option : (B)

Here, 

Sn = 3n+ 5n 

∴ S= 3+5 = 8 

∴ a1 = S1 = 8 

And S= 3×22+5×2 = 22 

Now,

a2 = S2 - S1 = 22-8 = 14 

∴ d = a2-a= 14-8 = 6 

Now, 

an = a1+(n-1)d 

∴ 164 = 8+(n-1)6 

∴ 156 = (n-1)6 

∴ 26 = n-1 

∴ n = 27

Welcome to Sarthaks eConnect: A unique platform where students can interact with teachers/experts/students to get solutions to their queries. Students (upto class 10+2) preparing for All Government Exams, CBSE Board Exam, ICSE Board Exam, State Board Exam, JEE (Mains+Advance) and NEET can ask questions from any subject and get quick answers by subject teachers/ experts/mentors/students.

...