Determine whether each of these proposed definitions is a valid recursive definition of a function f from the set of nonnegative integers to the set of integers. if f is well defined, find a formula for f(n) when n is a non negative integer and prove that you formula is valid.
a) f(0) = 1, f(n) = -f(n-1) for n> =1
d) f(0) =0, f(1) = 1, f(n) = 2f(n-1) for n> 1
e) f(0) = 2, f(n) = f(n-1) if n is odd and n> =1 and f(n) = 2f(n-2) if n> =2

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drop tower at kings dominion in doswell, virginia, ascends a 305-foot tower and drops 272 feet, while drop tower at kings island in kings mills, ohio, rises up a 315-foot tower and falls 264 feet

explanation: