Question

40 баллов! Срочно! Решите

Answer 1

Ответ:

$(3\sqrt3+2\sqrt7+\sqrt{21}+6)(3\sqrt3+2\sqrt7-\sqrt{21}-6)=\\\\=\Big((3\sqrt3+2\sqrt7)+(\sqrt{21}+6)\Big)\Big((3\sqrt3+2\sqrt7)-(\sqrt{21}+6)\Big)=\\\\=(3\sqrt3+2\sqrt7)^2-(\sqrt{21}+6)^2=\\\\=(27+8\sqrt{21}+28)-(21+12\sqrt{21}+36)=\\\\=55+8\sqrt{21}-57-12\sqrt{21}=\\\\=-2-4\sqrt{21}$