Question

(Корень3+Корень7) (2*Корень3-корень7)

Answer 1

$(\sqrt{3}+ \sqrt{7})( 2\sqrt{3}- \sqrt{7})= \sqrt{3}* 2\sqrt{3}-\sqrt{3}*\sqrt{7}+\sqrt{7}*2\sqrt{3}-\sqrt{7}\sqrt{7}= \\ = 3*2-\sqrt{3}\sqrt{7}+2\sqrt{3}\sqrt{7}-7=6-7+\sqrt{3}\sqrt{7}=-1+\sqrt{3}\sqrt{7}$