Se,face,cu,formula,radicalilor,compusi
[tex] \sqrt{a+ \sqrt{b} } = \sqrt{ \frac{a+ \sqrt{a ^{2}-b } }{2} } + \sqrt{ \frac{a- \sqrt{a ^{2}-b } }{2} } [/tex]
[tex]x= \sqrt{3+ \sqrt{8} } = \sqrt{ \frac{3+ \sqrt{9-8} }{2} } + \sqrt{ \frac{3- \sqrt{9-8} }{2} } = \sqrt{2} + \sqrt{1} =1+ \sqrt{2} [/tex]
[tex]y= \sqrt{ \frac{3+ \sqrt{9-8} }{2} } - \sqrt{ \frac{3- \sqrt{9-8} }{2} } = \sqrt{2} -1[/tex]
[tex] \sqrt{xy} = \sqrt{( \sqrt{2} +1)( \sqrt{2}-1) } = \sqrt{2-1} =1[/tex]
