Question

1 Вариант, пожалуйста

Answer 1

1.1)$x^2-5=x^2-(sqrt{5})^2=(x-sqrt{5})(x+sqrt{5});$
$1.2)4z-7=(sqrt{4z})^2-(sqrt{7})^2=(sqrt{4z}-sqrt{7})(sqrt{4z}+sqrt{7});$
$1.3)5+sqrt{5}=sqrt{25}+sqrt{5}=sqrt{5}(sqrt{5}+1);$
$1.4)sqrt{20}-sqrt{50}=sqrt{10}(sqrt{2}-sqrt{5}).$
$2.1) frac{y-9}{sqrt{y}-3}= frac{(sqrt{y})^2-3^2}{sqrt{y}-3}= frac{(sqrt{y}-3)(sqrt{y}+3)}{sqrt{y}-3}=sqrt{y}+3;$
$2.2) frac{sqrt{3}+3}{sqrt{6}+sqrt{2}}= frac{sqrt{3}+sqrt{9}}{sqrt{2}(sqrt{3}+1)}= frac{sqrt{3}(1+sqrt{3})}{sqrt{2}(1+sqrt{3})}= frac{sqrt{3}}{sqrt{2}};$