Question

Найдите значение выражения

$sqrt{25+4 sqrt{21} }$ + $sqrt{70-14 sqrt{21} }$

Answer 1

$sqrt{( sqrt{21}+2)^2 } + sqrt{(7- sqrt{21})^2 } =| sqrt{21} +2|+|7- sqrt{21} =$$sqrt{21} +2+7- sqrt{21} =9$