Final answer:
The output of the rule when given different inputs is found by substituting the input into the rule. The rule is a function because each input has a unique output.
Step-by-step explanation:
To find the output of the rule, we substitute the given input into the rule:
(a) When the input is 3, we have f(3) = 2(3) - 5 = 1.
(b) When the input is -4, we have f(-4) = 2(-4) - 5 = -13.
(c) Yes, the rule is an example of a function. A function is a relation in which each input (x-value) has exactly one output (y-value). In this rule, each input corresponds to a unique output, so it satisfies the definition of a function.