Question

.................Даю 30 баллов

Answer 1

$1) \: ( \sqrt{20} - \sqrt{5} ) \times \sqrt{5} = \sqrt{20} \times \sqrt{5} - \sqrt{5} \times \sqrt{5} = \sqrt{100} - \sqrt{25} = 10 - 5 = 5$
$2) \: ( \sqrt{7} - 2)( \sqrt{7} + 2) = 7 - 4 = 3$
$3) \: \sqrt{3} ( \sqrt{12} + \sqrt{3} ) = \sqrt{36} + 3 = 6 + 3 = 9$
$4) \: ( \sqrt{8} - \sqrt{5} )( \sqrt{8} + \sqrt{5} ) = 8 - 5 = 3$