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Re: Sn represent the sum of n terms of a certain sequence, where each term [#permalink]
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But it is mentioned that c>0; will that not make S(n+2) bigger?
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Re: Sn represent the sum of n terms of a certain sequence, where each term [#permalink]
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C> 0 is what in the end create the sequence

Turns out the sequence is a term + another one

Arithmetic Progression is a sequence obtained by adding or subtracting a constant from the previous terms. This leads to a common difference between each of the two consecutive terms.

So you have Sn+1+another term = Sn+2

In other words, we do have Sn+1+extra term=Sn+2+extra term=Sn+3 and so forth

Therefore in both quantities, Sn+1 is equal

Sn+1=Sn+2 because Sn+1=Sn+1 + extra term

Simplify we are left with just the extra term that we do not know is is positive, negative or zero

C>0 is used to create the sequence. It is another thing

Let me know if now is more clear
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Re: Sn represent the sum of n terms of a certain sequence, where each term [#permalink]
Carcass
what does c>0 represent here? if it does not mention c should be a +ve value
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Re: Sn represent the sum of n terms of a certain sequence, where each term [#permalink]
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As I said above C is the term to create the sequence.

See my explanation above.

Based on C the sequence could be different
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Sn represent the sum of n terms of a certain sequence, where each term [#permalink]
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The way I solved it was to take an example....(the fact that question says c>0, it wouldn't make any sense to assume +ve or -ve values for C..its absurd)

Assume c = 1 (since +ve)
For a series that would end in a negative number,
Eg .... -10, -9, -8, -7, -6 here if nth term is -8 then (n+2)th terms would be adding more -ve numbers to the sum and thus it would be lesser than sum of (n+1)th term....

This would reverse for a positive sequence of numbers.

Hence answer is D ..( rln cannot be determined)

Posted from my mobile device
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Re: Sn represent the sum of n terms of a certain sequence, where each term [#permalink]
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To understand the solution for this one, read the question more carefully:

Sn, represent the "SUM" of n terms of a certain sequence, where each term after the first term of the sequence is obtained by adding a constant c, where c > 0, in the preceding term.

Case 1: Since c is positive, consider c=1, and the first term in the sequence = -10.
So, the sequence would be -10,-9,-8,-7,..
Since Sn is the sum of the sequence, S1 = -10, S2 = -19. Here S1>S2.

Case 1: Since c is positive, consider c=1, and the first term in the sequence = 1.
So, the sequence would be 1,2,3, 4,..
Since Sn is the sum of the sequence, S1 = 1 , S2 = 3. Here S2>S1.

Hence, D.
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