[tex]a) \ \frac{x^{2}-9}{2-x}\cdot\frac{x-2}{3+x} = \frac{(x+3)(x-3)}{-(x-2)}\cdot\frac{x-2}{3+x} = -(x-3) = 3-x\\\\Z: \ \ x\neq -3 \ \ i \ \ x\neq 2[/tex]
[tex]b) \ \frac{-x^{2}+3x}{x-1}:\frac{2x-6}{x^{2}-1} = \frac{-x(x-3)}{x-1}:\frac{2(x-3)}{(x-1)(x+1)} = \frac{-x(x-3)}{x-1}\cdot\frac{(x-1)(x+1)}{2(x-3)} = -\frac{x(x+1)}{2}\\\\Z: \ \ x\neq -1 \ \ i \ \ x\neq 1 \ \ i \ \ x\neq 3[/tex]
