wiz-icon
MyQuestionIcon
MyQuestionIcon
1
You visited us 1 times! Enjoying our articles? Unlock Full Access!
Question

Let Sn denote the sum of first n terms of an AP and 3Sn=S2n. What is S3n:S2n equal to?

A
2:1
Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses
B
3:1
No worries! We‘ve got your back. Try BYJU‘S free classes today!
C
4:1
No worries! We‘ve got your back. Try BYJU‘S free classes today!
D
5:1
No worries! We‘ve got your back. Try BYJU‘S free classes today!
Open in App
Solution

The correct option is A 2:1
We know:
Sn=n2[2a+(n1)d)]
According to problem
3Sn=S2n
3n2[2a+(n1)d)]=2n2[2a+(2n1)d)]
6a+3nd3d=4a+4nd2d
2a=(n+1)d ........(1)
S3n:S2n=3n2[2a+(3n1)d)]2n2[2a+(2n1)d)]

=3[(n+1)d+(3n1)d)]2[(n+1)d+(2n1)d)]

=3d[(n+1)+(3n1))]2d[(n+1)+(2n1))]

=3d.4n2d.3n

=21

flag
Suggest Corrections
thumbs-up
0
Join BYJU'S Learning Program
similar_icon
Related Videos
thumbnail
lock
Sum of n Terms of an AP
MATHEMATICS
Watch in App
Join BYJU'S Learning Program
CrossIcon