QUESTION

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Please answer each question:


1. Why is $f$ not a function from $\mathbf{R}$ to $\mathbf{R}$ if a) $f(x)=1 / x$ ? b) $f(x)=\sqrt{x}$ ? c) $f(x)= \pm \sqrt{\left(x^{2}+1\right)}$ ? 2. Determine whether $f$ is a function from $\mathbf{Z}$ to $\mathbf{R}$ if a) $f(n)= \pm n$. b) $f(n)=\sqrt{n^{2}+1}$. c) $f(n)=1 /\left(n^{2}-4\right)$.

Public Answer

MLMWMC The First Answerer