Question

дам 35 баллов помогите пжлст
Все на картинке

Answer 1

$\displaystyle\bf\\1)\\\\\Big(2\sqrt{3} -1\Big)\Big(\sqrt{27} +3\Big)=\Big(2\sqrt{3} -1\Big)\Big(\sqrt{9\cdot 3} +3\Big)=\Big(2\sqrt{3} -1\Big)\Big(3\sqrt{3} +3\Big)=\\\\\\=18+6\sqrt{3} -3\sqrt{3} -3=15+3\sqrt{3} \\\\\\2)\\\\\frac{2}{a-4} -\frac{a+4}{a^{2} -6a+9} :\frac{a^{2} -16}{2a-6} =\frac{2}{a-4} -\frac{a+4}{(a-3)^{2} } :\frac{(a-4)(a+4)}{2(a-3)} =\\\\\\=\frac{2}{a-4} -\frac{a+4}{(a-3)^{2} } \cdot\frac{2(a-3)}{(a-4)(a+4)} =\frac{2}{a-4} -\frac{2}{(a-3)(a-4)} =$

$\displaystyle\bf\\=\frac{2a-6-2}{(a-3)(a-4)} =\frac{2a-8}{(a-3)(a-4)} =\frac{2(a-4)}{(a-3)(a-4)} =\frac{2}{a-3}$