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Bài 1: Tính
a, 1/2 x 2/3 x 3/4 = 1/4
b, 7/8 x 8/9 x 9/10 = 7/10
c, 5/14 x 7/15 x 28/7 = 2/3
d, 2 x 1/2 x 3 x 1/3 x 4 x 1/4 x 5 x 1/5 = 1
Bài 2: Tính
a, 7/20 - ( 5/8 - 3/5 ) = 7/20 - 1/40 = 14/40 - 1/40 = 13/40
b, 5/6 + ( 5/9 - 1/4 ) = 5/6 + 11/36 = 30/36 + 11/36 = 41/36
c, 9/10 - ( 2/5 + 3/10 ) + 7/20 = 9/10 - 7/10 + 7/20 = 2/10 + 7/20 = 4/20 + 7/20 = 11/20.
Bài 3: Tìm x:
a, 1/2 + x = 5/6
x = 5/6 - 1/2
x = 1/3
b, 5/6 - x = 1/3
x = 5/6 - 1/3
x = 1/2
c, x - 1/mấy vậy bạn
d, 1/3 x x = 1/6
x = 1/6 : 1/3
x = 1/2
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a)\(\frac{3}{7}\times\frac{1}{3}+\frac{10}{7}=\frac{1}{7}+\frac{10}{7}=\frac{11}{7}\)
b)\(\frac{9}{5}-\left(\frac{27}{36}-\frac{4}{36}\right)=\frac{9}{5}-\frac{23}{36}=\frac{324}{180}-\frac{115}{180}=\frac{209}{180}\)
a)3/7: 3+5x2/7
=1/7+10/7
=11/7
b)9/5-(3/4-1/9)
=9/5-23/36
=209/180
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a,4/5x2/9+1/5x2/9
=2/9*(4/5+1/5)
=2/9*1
=2/9
b)7/8:1/5-3/8:1/5
=(7/8-3/8):1/5
=1/2:1/5
=5/2
c)6/11x8/9+5/11x8/9
=(6/11+5/11)*8/9
=1*8/9
=8/9
d)11/12:2/3-3/12:2/3
=(11/12-3/12):2/3
=2/3:2/3
=1
MK sẽ giúp bn
a)\(\frac{4}{5}x\frac{2}{9}+\frac{1}{5}x\frac{2}{9}\)
\(=\left(\frac{4}{5}+\frac{1}{5}\right)x\frac{2}{9}\)
\(=1x\frac{2}{9}\)
\(=\frac{2}{9}\)
b)\(\frac{7}{8}:\frac{1}{5}-\frac{3}{8}:\frac{1}{5}\)
\(=\left(\frac{7}{8}-\frac{3}{8}\right):\frac{1}{5}\)
\(=\frac{5}{8}:\frac{1}{5}\)
\(=\frac{25}{8}\)
c)\(\frac{6}{11}x\frac{8}{9}+\frac{5}{11}x\frac{8}{9}\)
\(=\left(\frac{6}{11}+\frac{5}{11}\right)x\frac{8}{9}\)
\(=\frac{8}{9}x1\)
\(=\frac{8}{9}\)
d)\(\frac{11}{12}:\frac{2}{3}-\frac{3}{12}:\frac{2}{3}\)
\(=\left(\frac{11}{12}-\frac{3}{12}\right):\frac{2}{3}\)
\(=\frac{2}{3}:\frac{2}{3}\)
\(=1\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\left(\dfrac{6}{11}+\dfrac{5}{11}\right)\times\dfrac{3}{7}=\dfrac{11}{11}\times\dfrac{3}{7}=1\times\dfrac{3}{7}=\dfrac{3}{7}\)
\(\dfrac{3}{5}\left(\dfrac{7}{9}-\dfrac{2}{9}\right)=\dfrac{3}{5}\times\dfrac{5}{9}=\dfrac{1}{3}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
A. C1: (6/11 + 5/11) x 3/7 = 1 x 3/7 = 3/7
C2: (6/11 + 5/11) x 3/7 = 6/11 x 3/7 + 5/11 x 3/7 = 18/77 + 15/77 = 3/7
a)Cách 1:
(6/11+5/11)x3/7
=11/11x3/7
=1x3/7
=3/7
Cách 2:
(6/11+5/11)x3/7
=6/11x3/7+5/11x3/7
=18/77 + 15/77
=33/77
=3/7 (mink đã rút gọn)
k nhé
![](https://rs.olm.vn/images/avt/0.png?1311)
a) cách1 a) 3/5x7/9-3/5x2/9
=7/15-2/15
=1/3
cách 2 3/5x7/9-3/5x2/9
=3/5x(7/9-2/9)
=3/5x5/9
=1/3
a/ C1:
\(\frac{3}{5}\times\frac{7}{9}-\frac{3}{5}\times\frac{2}{9}=\frac{3}{5}\times\left(\frac{7}{9}-\frac{2}{9}\right)=\frac{3}{5}\times\frac{5}{9}=\frac{1}{3}\)
C2:
\(\frac{3}{5}\times\frac{7}{9}-\frac{3}{5}\times\frac{2}{9}=\frac{7}{15}-\frac{2}{15}=\frac{1}{3}\)
b/ C1:\(\left(\frac{6}{7}-\frac{4}{7}\right):\frac{2}{5}=\frac{2}{7}:\frac{2}{5}=\frac{5}{7}\)
C2: \(\frac{6}{7}:\frac{2}{5}-\frac{4}{7}:\frac{2}{5}=\frac{15}{7}-\frac{10}{7}=\frac{5}{7}\)
c/ C1: \(\frac{8}{15}:\frac{2}{11}+\frac{7}{15}:\frac{2}{11}=\frac{44}{15}+\frac{77}{30}=\frac{11}{2}\)
C2: \(\left(\frac{8}{15}+\frac{7}{15}\right):\frac{2}{11}=1:\frac{2}{11}=\frac{11}{2}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a)4/15
b)1/3
1) a ) \(\frac{2}{5}\times\frac{2}{3}=\frac{2\times2}{5\times3}=\frac{4}{15}\)
b) \(\frac{3}{8}\times\frac{8}{9}=\frac{3\times8}{8\times9}=\frac{1\times1}{1\times3}=\frac{1}{3}\)