Question

rút gọn các biểu thức sau:

1, (7\(\sqrt{18}\)+3\(\sqrt{27}\)+2\(\sqrt{12}\)):\(\sqrt{13}\)

2, \(\dfrac{\left(5\sqrt{2}+2\sqrt{5}\right)\left(\sqrt{3}-3\sqrt{2}_{ }\right)}{\sqrt{21}}\)

Answer 1

1: \(=\left(21\sqrt{2}+4\sqrt{3}+9\sqrt{3}\right):\sqrt{13}\)

\(=\dfrac{21\sqrt{2}}{\sqrt{13}}+\sqrt{3}=\dfrac{21\sqrt{26}+13\sqrt{3}}{13}\)

2: \(=\dfrac{\sqrt{10}\left(\sqrt{5}+\sqrt{2}\right)\cdot\sqrt{3}\left(1-\sqrt{6}\right)}{\sqrt{21}}\)

\(=\dfrac{\sqrt{30}\left(\sqrt{5}-\sqrt{30}+\sqrt{2}-2\sqrt{3}\right)}{\sqrt{21}}\)

\(=\dfrac{\sqrt{70}\left(\sqrt{5}-\sqrt{30}+\sqrt{2}-2\sqrt{3}\right)}{7}\)