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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Third choice

Step-by-step explanation:

i just did it on edgen and got it right

Answer: 7.5

Step-by-step 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