Exactly how many functions \(f: Q \rightarrow Q\) exist such that \(f(x+y)=f(x)+f(y)\) and \(f(x y)\)…

Exactly how many functions \(f: Q \rightarrow Q\) exist such that \(f(x+y)=f(x)+f(y)\) and \(f(x y)\) \(=f(x) f(y)\) for all \(x, y \in Q\) ?
  1. One
  2. Two
  3. Three
  4. Infinitely many

Solution

These functions are simultaneously satisfy for \(f(x)=x\) and \(f(x)=0 \forall x \in \mathbf{Q}\) Hecne, option (b) is correct.

Asked in: AP EAMCET 2020 (18 Sep Shift 2)

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