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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) $\frac{1}{6}:\frac{{21}}{9} = \frac{1}{6}:\frac{7}{3} = \frac{1}{6} \times \frac{3}{7} = \frac{3}{{42}} = \frac{1}{{14}}$
\(1-\left(\frac{12}{5}+y=\frac{8}{9}\right):\frac{16}{9}=0\)
\(1-\left(\frac{12}{5}+y-\frac{8}{9}\right)=0\times\frac{16}{9}\)
\(1-\left(\frac{12}{5}+y-\frac{8}{9}\right)=0\)
\(\frac{12}{5}+y-\frac{8}{9}=1-0\)
\(\frac{12}{5}-y+\frac{8}{9}=1\)
\(\frac{12}{5}-y=1-\frac{8}{9}\)
\(\frac{12}{5}-y=\frac{1}{9}\)
\(y=\frac{12}{5}-\frac{1}{9}\)
\(y=\frac{108}{45}-\frac{5}{45}\)
\(y=\frac{103}{45}\)
\(a,\frac{2}{5}+\frac{1}{6}+\frac{3}{5}\)
\(=\left(\frac{2}{5}+\frac{3}{5}\right)+\frac{1}{6}\)
\(=1+\frac{1}{6}\)
\(=\frac{7}{6}\)
Hok tốt!~
a) \(\frac{13}{19}+\frac{18}{19}+\frac{19}{19}=\left(\frac{13}{19}+\frac{17}{19}\right)+\frac{18}{19}=\frac{20}{19}+\frac{18}{19}=\frac{48}{19}\)
b) \(\frac{3}{5}+\frac{3}{16}+\frac{13}{16}=\left(\frac{3}{16}+\frac{13}{16}\right)+\frac{3}{5}=1+\frac{3}{5}=\frac{5}{5}+\frac{3}{5}=\frac{8}{5}\)
a) \(\frac{13}{19}+\frac{18}{19}+\frac{17}{19}\)
= \(\frac{31}{19}+\frac{17}{19}\)
= \(\frac{48}{19}.\)
b) \(\frac{3}{5}+\frac{3}{16}+\frac{13}{16}\)
= \(\frac{3}{5}+\left(\frac{3}{16}+\frac{13}{16}\right)\)
= \(\frac{3}{5}+\frac{16}{16}\)
= \(\frac{3}{5}+1\)
= \(\frac{3}{5}.\)
4/5 : 2/9 x 2/9 : 4/5
= 4/5 x 9/2 x 2/9 x 5/4
= ( 4/5 x 5/4 ) x ( 9/2 x 2/9 )
= 1x1
= 1
\(\frac{4}{5}:\frac{2}{9}\times\frac{2}{9}:\frac{4}{5}\)
\(=\frac{4}{5}\times\frac{9}{2}\times\frac{2}{9}\times\frac{5}{4}\)
\(=\left(\frac{4}{5}\times\frac{5}{4}\right)\times\left(\frac{2}{9}\times\frac{9}{2}\right)\)
\(=1\times1\)
\(=1\)
\(\frac{5}{6}:\frac{8}{9}-\frac{3}{4}:\frac{8}{9}\)
\(=\left(\frac{5}{6}-\frac{3}{4}\right):\frac{8}{9}\)
\(=\frac{1}{12}:\frac{8}{9}\)
\(=\frac{1}{12}\times\frac{9}{8}\)
\(=\frac{3}{32}\)
(\(\frac{5}{6}\)-\(\frac{3}{4}\)) : \(\frac{8}{9}\)
=\(\frac{1}{12}\): \(\frac{8}{9}\)
=\(\frac{3}{32}\)
k nhé, sau đó kb lun!
\(\frac{3}{4}:\frac{5}{6}+\frac{1}{4}:\frac{5}{6}\)
\(=\left(\frac{3}{4}+\frac{1}{4}\right):\frac{5}{6}\)
\(=1:\frac{5}{6}\)
\(=1\times\frac{6}{5}\)
\(=\frac{6}{5}\)
\(\frac{3}{4}:\frac{5}{6}+\frac{1}{4}:\frac{5}{6}\)
\(=\left(\frac{3}{4}+\frac{1}{4}\right):\frac{5}{6}\)
\(=1:\frac{5}{6}\)
\(=1\times\frac{6}{5}\)
\(=\frac{6}{5}\)
a: Ta có:
\(\left(\dfrac{2}{5}+\dfrac{1}{5}\right)+\dfrac{1}{5}=\dfrac{3}{5}+\dfrac{1}{5}=\dfrac{4}{5}\)
\(\dfrac{2}{5}+\left(\dfrac{1}{5}+\dfrac{1}{5}\right)=\dfrac{2}{5}+\dfrac{2}{5}=\dfrac{4}{5}\)
\(\dfrac{4}{5}=\dfrac{4}{5}\). Vậy \(\left(\dfrac{2}{5}+\dfrac{1}{5}\right)+\dfrac{1}{5}=\dfrac{2}{5}+\left(\dfrac{1}{5}+\dfrac{1}{5}\right)\)
Ta có:
\(\left(\dfrac{2}{9}+\dfrac{5}{9}\right)+\dfrac{1}{9}=\dfrac{7}{9}+\dfrac{1}{9}=\dfrac{8}{9}\)
\(\dfrac{2}{9}+\left(\dfrac{5}{9}+\dfrac{1}{9}\right)=\dfrac{2}{9}+\dfrac{6}{9}=\dfrac{8}{9}\)
\(\dfrac{8}{9}=\dfrac{8}{9}\). Vậy \(\left(\dfrac{2}{9}+\dfrac{5}{9}\right)+\dfrac{1}{9}=\dfrac{2}{9}+\left(\dfrac{5}{9}+\dfrac{1}{9}\right)\)
b: \(\left(\dfrac{1}{3}+\dfrac{2}{3}\right)+\dfrac{4}{3}=\dfrac{3}{3}+\dfrac{4}{3}=\dfrac{7}{3}\)
\(\dfrac{1}{3}+\left(\dfrac{2}{3}+\dfrac{4}{3}\right)=\dfrac{1}{3}+\dfrac{6}{3}=\dfrac{7}{3}\)
\(\dfrac{7}{3}=\dfrac{7}{3}\). Vậy \(\left(\dfrac{1}{3}+\dfrac{2}{3}\right)+\dfrac{4}{3}=\dfrac{1}{3}+\left(\dfrac{2}{3}+\dfrac{4}{3}\right)\)
Đề của anh bị sai mới đúng chứ ạ? Anh Đạt ghi là \(\left(\dfrac{2}{9}+\dfrac{5}{9}\right)+\dfrac{1}{9}\) chứ có phải \(\dfrac{2}{5}\) đâu ạ?
\(\frac{3}{4}.\frac{8}{9}.\frac{15}{16}.\frac{24}{25}.\frac{35}{36}\)
\(=\frac{3.2.4.3.5.4.6.5.7}{2.2.3.3.4.4.5.5.6.6}=\frac{7}{2.6}\)
\(=\frac{7}{12}\)
\(=\frac{1\cdot3\cdot2\cdot4\cdot3\cdot5\cdot4\cdot6\cdot5\cdot7}{2\cdot2\cdot3\cdot3\cdot4\cdot4\cdot5\cdot5\cdot6\cdot6}\)
\(=\frac{1\cdot7}{2\cdot6}\)
\(=\frac{7}{12}\)
a: =20/90+15/90+54/90=89/90
b: =(9/13+4/13)+2/3=1+2/3=5/3