Answer:
f(4) = 0
Step-by-step explanation:
For many sequences that involve recursive formulas, the quickest way to find the value of a given term is to evaluate those leading up to it. That seems to be the case here.
The next term after the one given is ...
f(2) = f(1)² -1 = 1² -1 = 0
Then we have ...
f(3) = f(2)² -1 = 0² -1 = -1
f(4) = f(3)² -1 = (-1)² -1 = 0
The value of f(4) is 0.
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Additional comment
Now that we have seen a few terms of the sequence, we can write an explicit formula for the terms after the first:
f(n) = (-1 +(-1)^n)/2 . . . integer n ≥ 2
