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The sequence S is defined by Sn = Sn – 1 + Sn – 2 + Sn – 3 –
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25 Jul 2018, 17:29
25 Jul 2018, 17:29
Expert Reply
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Question Stats:
84% (01:54) correct
15% (02:43) wrong based on 45 sessions
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The sequence S is defined by \(S_n = S_{n – 1} + S_{n – 2} + S_{n – 3} – 5\) for each integer n ≥ 4. If \(S_1 = 4\), \(S_2 = 0\), and \(S_4 = –4\), what is the value of \(S_6\)?
(A) –2
(B) –12
(C) –16
(D) –20
(E) –24
(A) –2
(B) –12
(C) –16
(D) –20
(E) –24
Re: The sequence S is defined by Sn = Sn – 1 + Sn – 2 + Sn – 3 –
[#permalink]
08 Jan 2020, 16:44
08 Jan 2020, 16:44
Expert Reply
Starting from what we do know.
\(S_1=4\)
\(S_2=0\)
\(S_4=-4\)
Find \(S_3\)
\(S_4=S_3+S_2+S_1-5\)
\(-4=S_3+4+0-5\)
\(S_3=-3\)
Substitute the value in the formula to find \(S_5\) and \(S_6\)
E is the answer
\(S_1=4\)
\(S_2=0\)
\(S_4=-4\)
Find \(S_3\)
\(S_4=S_3+S_2+S_1-5\)
\(-4=S_3+4+0-5\)
\(S_3=-3\)
Substitute the value in the formula to find \(S_5\) and \(S_6\)
E is the answer
gmatclubot
Re: The sequence S is defined by Sn = Sn – 1 + Sn – 2 + Sn – 3 – [#permalink]
08 Jan 2020, 16:44
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