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

If Sn denotes the sum of first n terms of an A.P. and S3nSn1S2nS2n1=31, then the value of n is

Open in App
Solution

Given: S3nSn1S2nS2n1=31
3n2[2a+(3n1)d]n12[2a+(n2)d]T2n=31 (S2nS2n1=T2n)2a(3n(n1))+d(3n(3n1)(n1)(n2))2T2n=312a(2n+1)+d(8n22)2T2n=312(2n+1)[a+(2n1)d]2T2n=31(2n+1)T2nT2n=312n+1=31n=15

flag
Suggest Corrections
thumbs-up
0
Join BYJU'S Learning Program
Join BYJU'S Learning Program
CrossIcon