ข้อ 3)
$\frac{1}{\sqrt{2} } + \frac{1}{\sqrt{3} } - \frac{2}{\sqrt{2} + \sqrt{3} + \sqrt{5}} $
$\frac{\sqrt{3} (\sqrt{2} + \sqrt{3} + \sqrt{5}) + \sqrt{2} (\sqrt{2} + \sqrt{3} + \sqrt{5}) - 2 \sqrt{2} \sqrt{3} }{\sqrt{2} \sqrt{3} (\sqrt{2} + \sqrt{3} + \sqrt{5}) }$
$\frac{(\sqrt{6} + 3 + \sqrt{15}) + ( 2 + \sqrt{6} + \sqrt{10}) - 2 \sqrt{6}}{\sqrt{6} (\sqrt{2} + \sqrt{3} + \sqrt{5}) }$
$\frac{(\sqrt{10} + \sqrt{15} + 5 ) }{\sqrt{6} (\sqrt{2} + \sqrt{3} + \sqrt{5}) }$
$\frac{(\sqrt{10} + \sqrt{15} + \sqrt{25} ) }{\sqrt{6} (\sqrt{2} + \sqrt{3} + \sqrt{5}) }$
$\frac{\sqrt{5} (\sqrt{2} + \sqrt{3} + \sqrt{5} ) }{\sqrt{6} (\sqrt{2} + \sqrt{3} + \sqrt{5}) }$
$\sqrt{\frac{5}{6} } $
|