[tex]a = \frac{ \sqrt{6} }{ \sqrt{8} } + \frac{ \sqrt{54} }{ \sqrt{32} } \: \: \: b = \frac{1}{ \sqrt{3} } - \frac{2}{ \sqrt{12} } + \frac{1}{ \sqrt{27} } \: \: \: \: \: \: \: \: a \times b = ...........[/tex]
va rog dau coroana ​