Q. 65.0( 2 Votes )

# If f: A → B is an injection such that range of f = {a}. Determine the number of elements in A.

Answer :

**TIP:** – __One – One Function__: – A function is said to be a one – one functions or an injection if different elements of A have different images in B.

So, is One – One function

⇔ a≠b

⇒ f(a)≠f(b) for all

⇔ f(a) = f(b)

⇒ a = b for all

Here, Range {f} = {a}

Since it is injective map, different elements have different images.

Thus A has only one element

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