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a: \(=\dfrac{5}{14}\left(\dfrac{2}{9}+\dfrac{7}{9}+1\right)=\dfrac{5}{14}\cdot2=\dfrac{5}{7}\)
b: \(=\dfrac{6}{8}\left(\dfrac{6}{7}-6\right)=\dfrac{6}{8}\cdot\dfrac{-36}{7}=\dfrac{-216}{56}=\dfrac{-27}{7}\)
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1.\(\dfrac{8}{11}+\dfrac{8}{33}\times\dfrac{3}{4}=\dfrac{8}{11}+\dfrac{8\times3}{33\times4}=\dfrac{8\times12}{11\times12}+\dfrac{8\times3}{33\times4}=\dfrac{8\times15}{132}=\dfrac{120}{132}=\dfrac{10}{11}\)
2.\(\dfrac{7}{9}\times\dfrac{3}{14}:\dfrac{5}{8}=\dfrac{7}{9}\times\dfrac{3}{14}\times\dfrac{8}{5}=\dfrac{4}{15}\)
3.\(\dfrac{5}{12}-\dfrac{7}{32}:\dfrac{21}{16}=\dfrac{5}{12}-\dfrac{7}{32}\times\dfrac{16}{21}=\dfrac{5}{12}-\dfrac{1}{6}=\dfrac{5-2}{12}=\dfrac{3}{12}=\dfrac{1}{4}\)
`@V.Tr.V`
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4/5 x 15/11 x 2/9 = 8/33
4/7 x 2/5 + 4/7 x 3/5 = 4/7
( 5/7 + 7/8 ) x 2 = 89/28
2/14 + 3/7 - 3/14 x 2 = 1/7
tk mình nhé, mk nhanh nhất
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5/9x12/7=20/21
6/5:8/3=9/20
9/20x5/12=3/16
15/16:25/24=9/10
14x5/21=10/3
10:5/3=6
5/3:10=1/6
5/9 x 12/7 = 60/63
6/5 : 8/3 = 6/5 x 3/8 = 9/20
9/20 x 5/12 = 3/16
15/16 : 25/24 = 15/16 x 24/25 = 9/10
14 x 5/21 = 60/21
10 : 5/3 = 10 x 3/5 = 6
5/3 : 10 = 5/3 x 1/10 = 1/6
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a, \(\left(\frac{4}{9}.\frac{3}{7}\right).\frac{7}{4}=\frac{4}{9}\left(\frac{3}{7}.\frac{7}{4}\right)=\frac{4}{9}.\frac{3}{4}=\frac{3}{9}=\frac{1}{3}\)
b, \(\left(\frac{6}{5}.\frac{4}{5}\right).\frac{25}{16}=\frac{6}{5}\left(\frac{4}{5}.\frac{25}{16}\right)=\frac{6}{5}.\frac{5}{4}=\frac{6}{4}=\frac{3}{2}\)
c, \(\left(\frac{7}{8}.\frac{16}{9}\right).\frac{3}{14}=\frac{7}{8}\left(\frac{16}{9}.\frac{3}{14}\right)=\frac{7}{8}.\frac{8}{21}=\frac{7}{21}=\frac{1}{3}\)
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( 4/9 x 3/7 ) x 7/4 = 4/9 x ( 3/7 x 7/4 ) =4/9 x 21/28 = 84/252
( 6/5 x 4/5 ) x 25/16 = ( 25/16 x 4/5 ) x 6/5 = 100/80 x 6/5 = 600/400
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Bài 2:
Sau 2 giờ con ốc sên bò được:
1/5+1/6=11/30(cây cột)
Sau 2 giờ thì con ốc sên còn phải bò:
1-11/30=19/30(cây cột)
9/7 / 3/5
=15/7
5/21 / 5/3 + 6/7
=1/7+6/7
=1
8/7 - 9/14 = 1/2
9/7 / 3/5 =???
5/21 / 5/3 + 6/7 = ??/
x / 100 = 250
x=25000
3/7 x X =5/14
x=5/6