Question

calculate rad21-8ra5 (totul sub un radical)

Answer 1

Formula:$\sqrt{21-8 \sqrt{5}$
a=21
b=8V5=>V320
c=$\sqrt{ a^{2} -b$
=>c=V121=11

$\sqrt{ \frac{21+11}{2} } - \sqrt{ \frac{21-11}{2} }$
=>4-$\sqrt{5}$