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18725:206=90 dư 185

3160:56=56 dư 3

41982:206=203 dư 82

\(=\dfrac{\dfrac{3}{7}+\dfrac{3}{5}-\dfrac{3}{4}}{\dfrac{2}{5}-\dfrac{2}{4}+\dfrac{2}{7}}-\dfrac{\dfrac{1}{8}+\dfrac{1}{6}-\dfrac{1}{2}}{\dfrac{3}{6}-\dfrac{3}{2}+\dfrac{3}{8}}=\dfrac{3}{2}-\dfrac{1}{3}=\dfrac{7}{6}\)

rút gọn

= \(\dfrac{3}{2}-\dfrac{1}{3}\)

= \(\dfrac{7}{6}\)

75 + 23 =98

\(=\dfrac{1}{120}-\dfrac{2}{3}\left(\dfrac{1}{30}-\dfrac{1}{33}+\dfrac{1}{33}-\dfrac{1}{36}+...+\dfrac{1}{117}-\dfrac{1}{120}\right)\)

\(=\dfrac{1}{120}-\dfrac{2}{3}\left(\dfrac{1}{30}-\dfrac{1}{120}\right)\)

\(=-\dfrac{1}{120}\)

\(\sqrt{50-\sqrt{18}}=\sqrt{50-3\sqrt{2}}\)

\(\sqrt{50-\sqrt{18}}=\sqrt{5\sqrt{2}-3\sqrt{2}}\)

\(=\sqrt{\left(5-3\right)\sqrt{2}}=\sqrt{2\sqrt{2}}\)

`\sqrt{48}-\sqrt{3}=\sqrt{4^2 . 3}-\sqrt{3}=4\sqrt{3}-\sqrt{3}=3\sqrt{3}`

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Giúp mình nha nha nha

     60 = 5 . 3 . 2²

     280 = 5 . 7 . 2³

=> ƯCLN ( 60 ; 280 ) = 5 . 2² = 20

BCNN(60;280)=840

*Cách làm:

Ta có: B(60)={0;60;120;180;....;780;840...}

           B(280)={0;280;840;1120....}

=> BCNN(60;280) = 840 (khác 0)