# To be or not to be

Algebra Level pending

If $$f: S \to T$$, $$S = \{1, 2, 3, 4\}$$, $$T = \{5, 6, 7\}$$, $$f(1) = 5, f(2) = 6, f(3) = 7$$, then $$f$$ is injective.

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