webby

@webby

  • vaibhav
  • 34 karma
webby
vaibhav @webby
what is the sum of 51x52, 52x53, 53x54...100x101?
webby
vaibhav @webby

@Bing05 could you tell me how you generally find the nth term of a series(any series)..do you follow any method or is it just hit and trial?

webby
vaibhav @webby
what is the sum of 51x52, 52x53, 53x54...100x101?

what is the sum of

51x52, 52x53, 53x54...100x101? 

  • 9Comments
  • @webby it is in the form n(n+1) = n^2+n , no hit and tria.... 12 Oct.
  • 51 * (51+1) + 52 * (52 + 1) ................ which is 51.... 12 Oct.
  9 Comments
Bing05
Max S @Bing05 13

@webby summation of first 100 terms  - summation of first 50 terms ( nth term = n^2+n)

webby
vaibhav @webby 34

@Bing05 could you tell me how you generally find the nth term of a series(any series)..do you follow any method or is it just hit and trial?

Bing05
Max S @Bing05 13

@webby it is in the form n(n+1) = n^2+n , no hit and trial......but u can verify with the few terms given , first sum up 100 terms using n(n+1)(2n+1)/6 and n(n+1)/2 and subtract it from summation of first 50 terms..generally series are in AP,GP,HP or AG or some differences in pattern upto 2 degree or more.

rahul.doodi1
Rahul Doodi @rahul.doodi1 14

51 * (51+1) + 52 * (52 + 1) ................

which is 51^2 + 52^2 +......... 100^2 + ( 51 + 52........+100)

Summation and get

how many 3 digit natural nos  have less than 5 prime factors?

  • 7Comments
  • 900. 12 Oct.
  • 999 -> 3^2*11^2 100 - > 5^2 * 2^2 999-101=900. 12 Oct.
webby
vaibhav @webby
how to find the unit digit of (1273)^122!?
webby
vaibhav @webby

so what is the ans of this ques: (123)^987! +(987)^123! ? will it be 2?

how to find the unit digit of (1273)^122!?

  • 12Comments
  • 1. 08 Oct.
  • . 09 Oct.
webby
vaibhav @webby
A nd B participated in a race. For the first hr their speed is same . Aftr that A increased his speed by 5% every hr. B increased his speed by 1% in first hr, by 3% in next hr, by 5% in next hr and so on. At what time B will overtake A. Plz give ans with solution.
webby
vaibhav @webby

3) Aftr 4 hrs 10 min 4) None of these

webby
vaibhav @webby
A nd B participated in a race. For the first hr their speed is same . Aftr that A increased his speed by 5% every hr. B increased his speed by 1% in first hr, by 3% in next hr, by 5% in next hr and so on. At what time B will overtake A. Plz give ans with solution.
webby
vaibhav @webby

1) Aftr 5 hrs 2) aftr 3 hrs 20 mins

webby
vaibhav @webby
A nd B participated in a race. For the first hr their speed is same . Aftr that A increased his speed by 5% every hr. B increased his speed by 1% in first hr, by 3% in next hr, by 5% in next hr and so on. At what time B will overtake A. Plz give ans with solution.
webby
vaibhav @webby

5 hrs is in the options but it is not the correct ans..OA is none of these...so I don't know the exact ans.