$\text{Đáp án + Giải thích các bước giải}$
$\text{2a) $\dfrac{x}{2x-4}$ - $\dfrac{2}{2x-4}$}$
$\text{= $\dfrac{x-2}{2x-4}$}$
$\text{= $\dfrac{x-2}{2(x-2)}$}$
$\text{= $\dfrac{1}{2}$}$
$\text{2b) $\dfrac{3}{x-3}$ : $\dfrac{6}{x²-9}$}$
$\text{= $\dfrac{3}{x-3}$ . $\dfrac{x²-9}{6}$}$
$\text{= $\dfrac{3}{x-3}$ . $\dfrac{(x-3)(x+3)}{6}$}$
$\text{= $\dfrac{3.(x-3)(x+3)}{6(x-3)}$}$
$\text{= $\dfrac{x+3}{2}$ }$
