a) Đk: $x-3x+2\ne0\Leftrightarrow -2x+2\ne0$
$\Leftrightarrow x\ne1$
Txđ: $D=\mathbb R\backslash\{1\}$
b) $\left\{ \begin{array}{l} x+2\ge0 \\ x-3\ge0 \end{array} \right .$
$\Leftrightarrow x\ge3$
Txđ: $D=[3;+\infty)$
c) Đk:
$\left\{ \begin{array}{l} x-2\ge0 \\ x+3\ne0\end{array} \right .\Rightarrow \left\{ \begin{array}{l} x\ge2 \\x\ne-3 \end{array} \right .$
$\Rightarrow x\ge2$
Txđ: $D=[2;+\infty)$
d) $\left\{ \begin{array}{l} x-3\ge0 \\ x+2>0\end{array} \right .\Rightarrow \left\{ \begin{array}{l} x\ge3 \\ x>-2\end{array} \right .$
$\Rightarrow x\ge3$
Txđ: $D=[3;+\infty)$
e) $x-5\ne0\Leftrightarrow x\ne5$
Txđ: $D=\mathbb R\backslash\{5\}$
