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Numerical Ability
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what is the sum of 4+18+48+100+180+284+448+....up to 28terms
Read Solution (Total 7)
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- 180670
the series is " n[(n+1)^2] " in this pattern
Case 1 put n=1
u will get "4"
Case 2 put n="2"
u will get "18
Case 3 put n="3"
u will get "48"
and so on
put n=28 to get ans= 180670 - 10 years agoHelpfull: Yes(36) No(4)
- 180670
the series is n[(n+1)^2]...apply the summation formula till n=28
(n^2)[(n+1)^2]/4 + n(n+1)/2 + 2n(n+1)(2n+1)/6
put n=28 to get ans= 180670 - 10 years agoHelpfull: Yes(11) No(1)
- sorry sum=180670
- 10 years agoHelpfull: Yes(4) No(2)
- ans:188384
its n term is n(n+1)^2 =n^3+2n^2+n
so sum upto n=28th term = (n(n+1)/2)^2 +2n(n+1)(2n+1)/6 +n(n+1)/2
put n=28 u get sum=188384 - 10 years agoHelpfull: Yes(3) No(5)
- let n=28 n[(n+1)^2]=23548
- 10 years agoHelpfull: Yes(1) No(0)
- ans:23548
- 10 years agoHelpfull: Yes(0) No(0)
- n(n+1)^2=28(29)^2=23548
- 8 years agoHelpfull: Yes(0) No(0)
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