It is given that f: R → R be defined as f (x) = 3x.
Let x, y ϵ R such that f(x) = f(y).
⇒ 3x = 3y
⇒ x = y
⇒ f is one–one.
Also, for any real number (y) in co–domain R, there exists in R such that
Therefore, f is onto.
Therefore, function f is one-one and onto.
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