[tex]\displaystyle\bf\\1)\\\\\frac{\sqrt{a} -3}{a-6\sqrt{a}+9 } =\frac{\sqrt{a} -3}{(\sqrt{a} )^{2} -2\cdot\sqrt{a}\cdot 3+3^{2} } =\frac{\sqrt{a} -3}{(\sqrt{a}-3)^{2} } =\frac{1}{\sqrt{a}-3 }[/tex]

Ответ :  Г

[tex]\displaystyle\bf\\2)\\\\\frac{\sqrt{a} +3}{9-a } =\frac{\sqrt{a} +3}{3^{2}-(\sqrt{a})^{2} }=\frac{\sqrt{a}+3 }{(3-\sqrt{a})\cdot(3+\sqrt{a} ) } =\frac{1}{3-\sqrt{a} }=-\frac{1}{\sqrt{a}-3 }[/tex]

Ответ :  B

[tex]\displaystyle\bf\\3)\\\\\frac{9-3\sqrt{a} }{3\sqrt{a}-a } =\frac{3^{2} -3\sqrt{a} }{3\sqrt{a}-(\sqrt{a})^{2} } =\frac{3\cdot(3-\sqrt{a}) }{\sqrt{a} \cdot(3-\sqrt{a}) } =\frac{3}{\sqrt{a} }[/tex]

Ответ : Б