The fibonacci sequence is f(n) = f(n – 1) + f(n – 2). if f(7) = 13 and f(8) = 21, which of the following is true? \ a. f(6) = 13 b. f(9) = 32 c. f(15) = 34 d. f(9) = 34

D. F(9) = 34

Step-by-step explanation:

Given,

F(n) =  F(n – 1) + F(n – 2)

For n = 8,

F(8) = F(8-1) + F(8-2) = F(7) + F(6)

⇒ 13 +  F(6)  = 21 ⇒ F(6) = 5

⇒ Option A is incorrect.

Now, for n = 9,

F(9) =  F(9 – 1) + F(9 – 2)= F(8) + F(7) = 21 + 13 = 34

⇒ Option B is incorrect.

F(15) ≠ F(9)

⇒ F(15) ≠ 34

⇒ Option C is incorrect.

Hence, only option D is correct.

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step-by-step explanation: