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Question 12

# Let f : R → R be defined as f(x) = 3x. Choose the correct answer.(A) f is one-one onto(B) f is many-one onto(C) f is one-one but not onto(D) f is neither one-one nor onto.

f: R → R defined as f(x) = 3x.

Let xy ∈ 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.

f is onto.

Hence, function f is one-one and onto.

The correct answer is A.

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