a: ĐKXĐ: x+1<>0
hay x<>-1
b: ĐKXĐ: \(\left\{{}\begin{matrix}1-x>=0\\2-x>=0\end{matrix}\right.\Leftrightarrow x< =1\)
c:ĐKXĐ: x-3>0
hay x>3
\(a,ĐKXĐ:x+1< >0\)
\(Hayx< >-1\)
\(b,ĐKXĐ:\left\{{}\begin{matrix}1-x>=0\\2-x>=0\end{matrix}\right.\Leftrightarrow x< =1\)
\(c,ĐKXĐ:X-3>0\)
-> Hay \(x>3\)