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GRE Prep Club Team Member
Joined: 20 Feb 2017
Posts: 2508
Given Kudos: 1053
GPA: 3.39
If S(n) is the sum of sequence 1, 2, 3, 4, ...n, in terms of n and S(n
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19 Apr 2022, 09:04
19 Apr 2022, 09:04
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Question Stats:
57% (02:57) correct
42% (01:33) wrong based on 7 sessions
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If S(n) is the sum of sequence 1, 2, 3, 4, ...n, in terms of n and S(n), S(2n)=?
(A) 2*S(n)
(B) n*S(n)
(C) 2n*S(n)
(D) 2S(n)+n^2
(E) S(n)+2n^2
(A) 2*S(n)
(B) n*S(n)
(C) 2n*S(n)
(D) 2S(n)+n^2
(E) S(n)+2n^2
Re: If S(n) is the sum of sequence 1, 2, 3, 4, ...n, in terms of n and S(n
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19 Apr 2022, 18:39
19 Apr 2022, 18:39
1
Quote:
If S(n) is the sum of sequence 1, 2, 3, 4, ...n, in terms of n and S(n), S(2n)=?
Using values, when n = 2
S(n) = S(2) = 1 + 2 = 3
S(2n) = S(4) = 1 + 2+ 3 + 4 = 10
substituting n =2 in the options, such that answer is 10
(A) 2*S(n) = 2 * S(2) = 2*3 = 6 wrong
(B) n*S(n) = 2 * S(2) = 6 wrong
(C) 2n*S(n) = 2*2*S(2) = 2*2*3 = 12 wrong
(D) 2S(n)+n^2 = 2*S(2) + 2^2 = 2*3 + 4 = 10 Correct
(E) S(n)+2n^2 = S(2) + 2*2^2 = 3 + 8 = 11 wrong
IMO D
gmatclubot
Re: If S(n) is the sum of sequence 1, 2, 3, 4, ...n, in terms of n and S(n [#permalink]
19 Apr 2022, 18:39
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