Question

De calculat: 
$\sqrt{19}- 6\sqrt{2} Radicalul de la 19 se prelungeste peste tot exercitiul.$, Cu radical dublu. 

Answer 1

        
$\sqrt{19-6 \sqrt{2}}= \\ \\ = \sqrt{18+1-6 \sqrt{2}}= \\ \\ =\sqrt{18-6 \sqrt{2}+1}= \\ \\ =\sqrt{(3 \sqrt{2})^{2}- 2*1*3\sqrt{2}+1^{2}}= \\ \\ = \sqrt{(3 \sqrt{2}-1)^{2}}= \\ \\ = 3 \sqrt{2}-1$