ĐKXĐ:
a/\(\left\{{}\begin{matrix}51-2x-x^2\ge0\\1-x\ne0\end{matrix}\right.\) \(\Rightarrow\left\{{}\begin{matrix}-1-2\sqrt{13}\le x\le-1+2\sqrt{13}\\x\ne1\end{matrix}\right.\)
b/ \(\left\{{}\begin{matrix}-3x^2+x+4\ge0\\x\ne0\end{matrix}\right.\) \(\Rightarrow\left\{{}\begin{matrix}-1\le x\le\frac{4}{3}\\x\ne0\end{matrix}\right.\)
c/ \(x+1>0\Rightarrow x>-1\)