Which element of series equal to zero

rengaraj

rengaraj

@rengaraj-89Rrct Oct 25, 2024
Sir / Madam,
My questions is,

The sum of 3rd and 15th elements of an arithmetic progression is equal to the sum of 6th, 11th and 13th elements of the same progression. Then which element of the series should necessarily be equal to zero?

Advance Thanks,
R.Rengaraj
{InfosysTrain-Q103 Pg26}

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  • Saandeep Sreerambatla

    Saandeep Sreerambatla

    @saandeep-sreerambatla-hWHU1M Jan 12, 2010

    Is it the 12th element?
  • rengaraj

    rengaraj

    @rengaraj-89Rrct Jan 13, 2010

    Sir,
    Can you explain your answer?
    R.Rengaraj
  • Saandeep Sreerambatla

    Saandeep Sreerambatla

    @saandeep-sreerambatla-hWHU1M Jan 13, 2010

    I solved it in this way..

    a+2d+a+14d = a+5d+a+10d+a+12d
    2a+16d = 3a+27d

    on solving it gives a+11d = 0

    This it 12th element!
  • rengaraj

    rengaraj

    @rengaraj-89Rrct Jan 14, 2010

    Sir,
    Your answer matches with the available choices.
    R.Rengaraj
  • sherya mathur

    sherya mathur

    @sherya-mathur-cI63wY Feb 18, 2010

    lets the first term of ap is a and difference is d
    then third term will be =a+2d
    15th will be=a+14d
    6th will be =a+5d
    11th will be =a+10d
    13th will be=a+12d
    then the equation will be as
    a+2d+a+14d = a+5d+a+10d+a+12d
    2a+16d = 3a+27d
    a+11d=0
    simply we can understand a+11d will be the 12th term of arithmetic progression
    so the correct answer is 12