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505-555 Level|   Sequences|      
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Bunuel
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The sequence a1, a2, a3,…, an is defined by an = an – 2 + an – 1 for a 25 Apr 2017, 03:23
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15% (low)

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84% (01:25) correct 16% (01:49) wrong based on 141 sessions

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The sequence \(a_1\), \(a_2\), \(a_3\), …, \(a_n\) is defined by \(an = a_{n – 2} + a_{n – 1}\) for all n > 2 . If \(a_3 = 2\) and \(a_5 = 5\), what is the value of \(a_6\)?

(A) 7
(B) 8
(C) 10
(D) 12
(E) 13
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B
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skothaka
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The sequence a1, a2, a3,…, an is defined by an = an – 2 + an – 1 for a 25 Apr 2017, 03:31
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a3=2, a5=5

a5 = a3+a4 = 2+a4 = 5
a4=3

a6=a5+a4 = 5+3 = 8

Correct me if I'm wrong :)
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mcmoorthy
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The sequence a1, a2, a3,…, an is defined by an = an – 2 + an – 1 for a 25 Apr 2017, 03:35
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a_5 =a_4+a_3
5=a_4 + 2
a_4=3
a_6 = a_5+a_4
a_6=5+3
a_6=8
Ans is B

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The sequence a1, a2, a3,…, an is defined by an = an – 2 + an – 1 for a 28 Apr 2017, 15:17
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Bunuel
The sequence \(a_1\), \(a_2\), \(a_3\), …, \(a_n\) is defined by \(an = a_{n – 2} + a_{n – 1}\) for all n > 2 . If \(a_3 = 2\) and \(a_5 = 5\), what is the value of \(a_6\)?

(A) 7
(B) 8
(C) 10
(D) 12
(E) 13

We are given that the nth term of a sequence is defined as: a(n) = a(n-2) + a(n-1).

We know that a(5) = 5 and that a(3) = 2; thus:

a(5) = a(3) + a(4)

5 = 2 + a(4)

3 = a(4)

We need to determine the value of a(6).

a(6) = a(4) + a(5)

a(6) = 3 + 5 = 8

Answer: B
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Bunuel
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