Question

$sqrt{54-14 sqrt{5} } *( sqrt{5}+7)$
Вычеслите

Answer 1

$sqrt{54-14 sqrt{5}}*( sqrt{5}+7)= sqrt{(54-14sqrt{5})*( sqrt{5}+7)^{2}}= \ = sqrt{(54-14sqrt{5})*(5+14 sqrt{5}+49)}=sqrt{(54-14sqrt{5})*(54+14 sqrt{5})}= \= sqrt{54^{2}-(14 sqrt{5})^{2}}= sqrt{1936}=44$