Ответ:

[tex]6 - 2\sqrt{21}[/tex]

Объяснение:

[tex](2\sqrt{3} - 2\sqrt{7} ) * \sqrt{3} = 2\sqrt{3} * \sqrt{3} - 2\sqrt{7} * \sqrt{3} = 2 * 3- 2\sqrt{21} = 6 - 2\sqrt{21}[/tex]