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Question

Question: Let {a<sub>n</sub>} (n ³ 1) be a sequence such that a<sub>1</sub> = 1, and 3a<sub>n+1</sub> – 3a<sub...

Let {an} (n ³ 1) be a sequence such that a1 = 1, and 3an+1 – 3an = 1 for all n ³ 1. Then a2002 is equal to-

A

666

B

667

C

668

D

669

Answer

668

Explanation

Solution

a1 = 1

3an+1 – 3an = 1

an + 1 = = ,

a2 = 13\frac { 1 } { 3 }

a3 = a2 + 13\frac { 1 } { 3 } = = 1 + 23\frac { 2 } { 3 }

a4 = a3 + 13\frac { 1 } { 3 } = 1+23+131 + \frac { 2 } { 3 } + \frac { 1 } { 3 } = 1 + 33\frac { 3 } { 3 }

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a2002 = 1 + 20013\frac { 2001 } { 3 } = 1 + 667 = 668