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The signum function f:R→Rf:R\to R, defined by

f(x)={−1,x<00,x=01,x>0f(x)=\begin{cases}-1, & x<0\\0, & x=0\\1, & x>0\end{cases} is: (Where R is set of real numbers)

Solution

✅ Correct Option: 4

Every positive real maps to 1, so ff is not one-one. Its range is only {−1,0,1}\{-1,0,1\}, a proper subset of RR, so ff is not onto either.

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