a) \(\dfrac{1}{3};\dfrac{1}{2};\dfrac{2}{3};\dfrac{1}{4};\dfrac{3}{4};\dfrac{1}{6};\dfrac{5}{6}\)
quy đồng các mấu số trên có mẫu chung là 12
ta có : \(\dfrac{1}{3}=\dfrac{4}{12}\)
\(\dfrac{1}{2}=\dfrac{6}{12}\)
\(\dfrac{2}{3}=\dfrac{8}{12}\)
\(\dfrac{1}{4}=\dfrac{3}{12}\)
\(\dfrac{3}{4}=\dfrac{9}{12}\)
\(\dfrac{1}{6}=\dfrac{2}{12}\)
\(\dfrac{5}{6}=\dfrac{10}{12}\)
b) \(\dfrac{2}{-7};\dfrac{1}{9};\dfrac{-2}{-9};\dfrac{8}{-21};\dfrac{-10}{21}\)
quy đồng mấu số trên có mẫu chung là 63
ta có \(\dfrac{2}{-7}=\dfrac{18}{-63}\)
\(\dfrac{1}{9}=\dfrac{7}{63}\)
\(\dfrac{-2}{-9}=\dfrac{-14}{-63}\)
\(\dfrac{8}{-21}=\dfrac{24}{-63}\)
\(\dfrac{-10}{21}=\dfrac{-30}{63}\)
a: \(\dfrac{1}{3}=\dfrac{1\cdot4}{3\cdot4}=\dfrac{4}{12}\)
\(\dfrac{1}{2}=\dfrac{1\cdot6}{2\cdot6}=\dfrac{6}{12}\)
\(\dfrac{2}{3}=\dfrac{2\cdot4}{3\cdot4}=\dfrac{8}{12}\)
\(\dfrac{1}{4}=\dfrac{1\cdot3}{4\cdot3}=\dfrac{3}{12}\)
\(\dfrac{3}{4}=\dfrac{3\cdot3}{4\cdot3}=\dfrac{9}{12}\)
\(\dfrac{1}{6}=\dfrac{1\cdot2}{6\cdot2}=\dfrac{2}{12}\)
\(\dfrac{5}{6}=\dfrac{5\cdot2}{6\cdot2}=\dfrac{10}{12}\)
b: \(\dfrac{2}{-7}=\dfrac{-2}{7}=\dfrac{-2\cdot9}{7\cdot9}=\dfrac{-18}{63}\)
\(\dfrac{1}{9}=\dfrac{1\cdot7}{9\cdot7}=\dfrac{7}{63}\)
\(\dfrac{-2}{-9}=\dfrac{2}{9}=\dfrac{2\cdot7}{9\cdot7}=\dfrac{14}{63}\)
\(\dfrac{8}{-21}=\dfrac{-8}{21}=\dfrac{-8\cdot3}{21\cdot3}=\dfrac{-24}{63}\)
\(\dfrac{-10}{21}=\dfrac{-10\cdot3}{21\cdot3}=\dfrac{-30}{63}\)
