Consider the numerical pyramid below, formed by simply putting down the series of odd numbers into a pyramid.

           1
         3   5
       7   9   11
    13  15  17   19
      . . .

Find a formula for the sum of the numbers in the nth row, and prove it.

hi sk .. i thought that i had proved it when i stated my solution..to clarify, my formula for the last number in row n-1 and by extension the first number in row n was based on the fact that by the end of row n-1, the number of odd numbers that would have been used up was 1+2+3+4....n-1
which is given by n(n-1)/2 ..therefore, the last number on row n-1 would be 2*(n(n-1)/2-1 since the generic formula for the xth odd number is given by 2*x-1 ... the rest of the solution is as i had already posted ... as a non-mathematician, my solution seemed simpler ...this is not to denigrate ur solution in any way

Posted by anand on 2003-10-17 04:21:07