[tex]a)2 \sqrt{2} \times (5 \sqrt{2} - 6 \sqrt{3} + \sqrt{6} ) = \\ = 10 \times 2 - 12 \sqrt{6} + 2 \sqrt{12} = \\ = 20 - 12 \sqrt{6} + 4 \sqrt{3} = \\ = 4( 5 -3 \sqrt{6} + \sqrt{3}) [/tex]
[tex]b)4 \sqrt{3} \times ( \sqrt{27} + \sqrt{75} - \sqrt{243} ) = \\ = 4 \sqrt{3} \times (3 \sqrt{3} + 5 \sqrt{3} - 9 \sqrt{3}) = \\ = 4 \sqrt{3} \times ( - \sqrt{3}) = \\ = - 12 [/tex]
Sper ca te-am ajutat...