Question

Упростите выражение:√√5+√21

Answer 1

$sqrt{5+sqrt{21}}=sqrt{dfrac{10+2sqrt{21}}{2}}=dfrac{sqrt{7+3+2cdot sqrt7cdot sqrt3}}{sqrt2}=dfrac{sqrt{(sqrt7+sqrt3)^2}}{sqrt2}=\\\=dfrac{|sqrt7+sqrt3|}{sqrt2}=dfrac{sqrt7+sqrt3}{sqrt2}; ;; ; ; ; Big(; dfrac{sqrt{14}+sqrt6}{2}; Big)$

Answer 2

см. https://znanija.com/task/36408729