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Number System
by mac 07 - Wednesday, 16 March 2016, 09:45 PM
  The sum of the first N natural numbers is equal to x^2 where x is an integer less than 100. Find the sum of all the possible values of N.

a)37
b)34
c)57
d)58

plz help
Re: Number System
by fyn sat - Friday, 25 March 2016, 07:51 PM
  is it 58......if yes then ..... desired values of N would be of the form n*(n+1)/2 such that it is a square of some number and to make it a square of a number v got to have an odd no. which is a square of some number and an even number such that its half is a square of some natural number...

1*2/2=1=1^2(N =1)

8*9/2=4*9=6^2(N=8)

49*50/2=49*25=35(N=49)

hence 49+1+8=58