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A sequence is defined recursively using the formula f(n + 1) = -0.5f(n). If the first term of the sequence is 120, what is f(5)?

-15

-7.5

7.5

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User Qspitzer
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2 Answers

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Answer:

Third choice

Explanation:

i just did it on edgen and got it right

User Cbeckner
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Answer: 7.5

Explanation:

The given formula tells us that the next term f(n+1) of the sequence is -0.5 times the previous term f(n)

First term of the sequence is f(1) = 120

Second term of the sequence is f(2) = f(1+1) = -0.5 f(1) = -0.5 (120) = -60

Third term of the sequence is f(3) = f(2+1) = -0.5 f(2) = -0.5 (-60) = 30

Fourth term of the sequence is f(4) = f(3+1) = -0.5 f(3) = -0.5 (30) = -15

Fifth term of the sequence is f(5) = f(4+1) = -0.5 f(4) = -0.5 (-15) = 7.5