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\(a,\dfrac{5}{13}\times\dfrac{4}{15}\times13=\dfrac{5\times4\times13}{13\times5\times3}=\dfrac{4}{3}\\ b,\left(\dfrac{3}{7}+\dfrac{5}{2}\right)\times\dfrac{7}{5}=\dfrac{3}{7}\times\dfrac{7}{5}+\dfrac{5}{2}\times\dfrac{7}{5}=\dfrac{3}{5}+\dfrac{7}{2}=\dfrac{6}{10}+\dfrac{35}{10}=\dfrac{41}{10}\\ c,\dfrac{1}{5}\times\dfrac{11}{18}+\dfrac{11}{18}\times\dfrac{3}{5}=\dfrac{11}{18}\times\left(\dfrac{1}{5}+\dfrac{3}{5}\right)=\dfrac{11}{18}\times\dfrac{4}{5}=\dfrac{22}{45}\)
a) $\frac{{14}}{{18}}:\frac{8}{9} = \frac{7}{9}:\frac{8}{9} = \frac{7}{9} \times \frac{9}{8} = \frac{{63}}{{72}} = \frac{7}{8}$
b) $\frac{9}{6}:\frac{3}{{10}} = \frac{3}{2}:\frac{3}{{10}} = \frac{3}{2} \times \frac{{10}}{3} = \frac{{30}}{6} = 5$
c) $\frac{4}{5}:\frac{{10}}{{15}} = \frac{4}{5}:\frac{2}{3} = \frac{4}{5} \times \frac{3}{2} = \frac{{12}}{{10}} = \frac{6}{5}$
d) $\frac{1}{6}:\frac{{21}}{9} = \frac{1}{6}:\frac{7}{3} = \frac{1}{6} \times \frac{3}{7} = \frac{3}{{42}} = \frac{1}{{14}}$
\(\frac{19}{15}+\frac{31}{23}-\frac{4}{15}-\frac{8}{23}\)
\(=\left(\frac{19}{15}-\frac{4}{15}\right)+\left(\frac{31}{23}-\frac{8}{23}\right)\)
\(=\frac{15}{15}+\frac{23}{23}\)
\(=1+1=2\)
\(\frac{19}{15}+\frac{31}{23}-\frac{14}{15}-\frac{8}{23}\)
\(=\frac{19}{15}-\frac{4}{15}+\frac{31}{23}-\frac{8}{23}\)
\(=1+1=2\)
chúc bạn học giỏi
27/15 + 6/8 =51/20
19/24 + 7/18 = 85/72
2/9 - 1/6 = 1/18
8/15 -1/3 = 1/5
60x [7/12+4/15]
60x153/180
=9180/180
b 1/2x2/3x3/4x4/5x5/6x6/7x7/8x8/9=40320/4032
a) \(\frac{7}{18}+\frac{4}{23}+\frac{11}{18}+\frac{19}{23}\)
\(=\left(\frac{7}{18}+\frac{11}{18}\right)+\left(\frac{4}{23}+\frac{19}{23}\right)\)
\(=1+1\)
\(=2\)
b) \(\frac{19}{15}+\frac{31}{23}-\frac{4}{15}-\frac{8}{23}\)
\(=\left(\frac{19}{15}-\frac{4}{15}\right)+\left(\frac{31}{23}-\frac{8}{23}\right)\)
\(=1+1\)
\(=2\)
ủng hộ tớ nha
a) \(\dfrac{16}{15}+\dfrac{7}{15}+\dfrac{4}{15}=\left(\dfrac{16}{15}+\dfrac{4}{15}\right)+\dfrac{7}{15}=\dfrac{20}{15}+\dfrac{7}{15}=\dfrac{27}{15}\)
b) \(\dfrac{5}{17}+\dfrac{7}{17}+\dfrac{13}{17}=\dfrac{5}{17}+\left(\dfrac{7}{17}+\dfrac{13}{17}\right)=\dfrac{5}{17}+\dfrac{20}{17}=\dfrac{25}{17}\)
\(\dfrac{15}{18}+\dfrac{8}{23}+\dfrac{3}{18}+\dfrac{15}{23}=\left(\dfrac{15}{18}+\dfrac{3}{18}\right)+\left(\dfrac{8}{23}+\dfrac{15}{23}\right)=1+1=2\)
\(\dfrac{15}{18}+\dfrac{8}{23}+\dfrac{3}{18}+\dfrac{15}{23}\)
\(=(\dfrac{15}{18}+\dfrac{3}{18})+(\dfrac{8}{23}+\dfrac{15}{23})\)
\(=1+1\)
\(=2\)