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Since

the domain of f(x) is the set of non-negative integers, because we can't feed a square root with negative inputs. So, you couldn't comput f(-9)
Unless you're allowed to use complex numbers, in that case we have

Which evaluates to

Answer:
Step-by-step explanation:
Answer:
-1/10
Step-by-step explanation:
after (.) we put zero in the denominator according to how many numbers are after .