Question

.................Даю 30 баллов

Answer 1

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