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Comment : Function quiz
Comment : This quiz is designed to test your knowledge of basic concepts in functions.
Comment : "One-to-one" is the opposite of "two-to-one" (a two-to-one function can map two different values in X to the same value in Y).
Comment : There are two correct answers supplied for this question.

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Question 1: Let f: X -> Y be a function. If we say that f is "one-to-one", this means that

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	Every x in X gets mapped to exactly one element in Y.
	For every x in X there is at most one y in Y such that f(x) = y.
	For every x in X there is at least one y in Y such that f(x) = y.
	For every y in Y there is some x in X such that f(x) = y.
	For every y in Y there is at most one x in X such that f(x) = y.
	For every y in Y there is exactly one x in X such that f(x) = y.
	f has an inverse f^{-1}.