подставив, получаем:

(sqrt{6})^3 * (sqrt{8})^3 - (sqrt{6} * sqrt{2})^3 = 6sqrt{6} * 8sqrt{8} - (6sqrt{6} * 2sqrt{2})= 48sqrt{48} - 12sqrt{12}= 48sqrt{12*4} - 12sqrt{12} = 96sqrt{12} - 12sqrt{12} = 84sqrt{12} = 84sqrt{4*3} = 168sqrt{3}