Answers

2014-11-02T20:44:25+05:30
Ans is 2403...............

0
too short for answering sorry i still can't thank's u
  • Brainly User
2014-11-02T23:14:44+05:30
Let s=2+3+6+11+18............tn
    s=    2+3+ 6 +11+18......tn-1+tn
subtract the above two equations and you will notice that difference is in A.P.
that is 1,3,5,7...and hence you can solve
0
very short sorry i can't thank u
see shubham,
you can subtract the above 2 equation which i have said and after that you will get Tn=1+3+5+7.......as i said earlier.so tn is n/2{2a+(n-1)d......this is the general term of the above ap.......now put the required values of a=1 and d=2 in Tn which i have written......you will get Tn as n^2-n...but still check the calculations ans now Sn is sigma Tn ans so sigma n^2 is n(n+1)(2n+1)/6 and sigma n is n(n+1)/2............but still check the calculations and on adding put n=50 and u are there....