$1)$ $\lim\limits_{x\to 2^-} \dfrac{x^2-3x+2}{\sqrt{2-x}}$
$=\lim\limits_{x\to 2^-} \dfrac{(1-x)(2-x)}{\sqrt{2-x}}$
$=\lim\limits_{x\to 2^-} (1-x).\sqrt{2-x}$
`=(1-2).\sqrt{2-2}=0`
$\\$
$2)$ $\lim\limits_{x\to 3^-}\dfrac{x^2-9}{\sqrt{(x^2+1)(3-x)}}$
$=\lim\limits_{x\to 3^-} \dfrac{(x-3)(x+3)}{\sqrt{(x^2+1)(3-x)}}$
$=\lim\limits_{x\to 3^-} \dfrac{-\sqrt{3-x}(x+3)}{\sqrt{x^2+1}}$
`=-(3-3).(3+3).\sqrt{3^2+1}=0`