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​Let (X,d) be a metric space and let f:X→X be a function such that:d(f(x),f(y))≤d(x,y
Question

Let (X,d) be a metric space and let f:XX be a function such that:d(f(x),f(y))d(x,y),for every x,yX.Which of the following statements is necessarily true?\text{Let } (X, d) \text{ be a metric space and let } f: X \to X \text{ be a function such that:}\\d(f(x), f(y)) \leq d(x, y), \quad \text{for every } x, y \in X.\\\text{Which of the following statements is necessarily true?}​​

A.

f is continuous .

B.

f is injective .

C.

f is surjective .

D.

f is injective if and only if  f is surjective .

Correct option is A

d(f(x),f(y))d(x,y), x,yX. is given ϵ>0, δ>0 for any cX such that d(f(x),f(c))<ϵ whenever d(x,c)<δ.Thus, f(x) is a continuous function.d(f(x), f(y)) \leq d(x, y), \; \forall \, x, y \in X.\ \text{is given}\\\implies \forall \, \epsilon > 0, \, \exists \, \delta >0 \text{ for any } c \in X \text{ such that }\\d(f(x), f(c)) < \epsilon \; \text{whenever} \; d(x, c) < \delta.\\\text{Thus, } f(x) \text{ is a continuous function.}​​

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