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a: \(=\left(\dfrac{4}{9}+\dfrac{5}{9}\right)+\left(\dfrac{1}{8}+\dfrac{7}{8}\right)=1+1=2\)
b: \(=\left(\dfrac{1}{6}+\dfrac{4}{6}+\dfrac{7}{6}\right)+\left(\dfrac{5}{12}+\dfrac{7}{12}\right)=2+1=3\)
\(a,=\dfrac{17}{12}\\ b,=\dfrac{3}{16}\\ c,=\dfrac{35}{72}\\ d,=\dfrac{3}{2}\)
a) \(\dfrac{2}{5}+\dfrac{7}{10}=\dfrac{4}{10}+\dfrac{7}{10}=\dfrac{11}{10}\)
b) \(\dfrac{6}{7}-\dfrac{5}{8}=\dfrac{48}{56}-\dfrac{35}{56}=\dfrac{13}{56}\)
c) \(\dfrac{3}{5}x\dfrac{15}{8}=\dfrac{45}{40}=\dfrac{9}{8}\)
d) \(\dfrac{1}{4}:\dfrac{3}{7}=\dfrac{1}{4}x\dfrac{7}{3}=\dfrac{7}{12}\)
bài 1
a)\(=\dfrac{16}{40}+\dfrac{15}{40}=\dfrac{31}{40}\)
b)\(=\dfrac{7}{6}-\dfrac{4}{6}=\dfrac{3}{6}=\dfrac{1}{2}\)
c)\(=\dfrac{30}{9}=\dfrac{10}{3}\)
d)\(=\dfrac{8}{5}\times\dfrac{7}{4}=\dfrac{56}{20}=\dfrac{14}{5}\)