Rút gọn

D

ducdao_pvt

$(4\sqrt{3} + 3\sqrt{2} + \sqrt{30})( \sqrt{30} + 5\sqrt{2} - 4\sqrt{5})$

$= 4\sqrt{3}.\sqrt{30} + 4\sqrt{3}.5\sqrt{2} - 4\sqrt{3}.4\sqrt{5} + 3\sqrt{2}.\sqrt{30} + 3\sqrt{2}.5\sqrt{2} - 3\sqrt{2}.4\sqrt{5} + \sqrt{30}.\sqrt{30} + \sqrt{30}.5\sqrt{2} - \sqrt{30}.4\sqrt{5}$

$= 4.3.\sqrt{10} + 20.\sqrt{6} - 16.\sqrt{15} + 3.2.\sqrt{15} + 3.5.2 - 12.\sqrt{10} + 30 + 2.5.\sqrt{15} - 4.5.\sqrt{6}$

$= 60$
 
B

braga

$(4\sqrt{3}+3\sqrt{2}+\sqrt{30})(\sqrt{30}+5\sqrt{2}-4\sqrt{5}) \\ =\sqrt{3}.\sqrt{5}.2.(\sqrt{3}+\sqrt{5}+\sqrt{8})(\sqrt{3}+\sqrt{5}-\sqrt{8}) \\ =2\sqrt{15}[(\sqrt{3}+\sqrt{5})^{2}-8]=2.\sqrt{15}.2.\sqrt{15}=60$
 
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