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Bài 1 : Tìm x
12/5 - x : 5/7 = 12/5
x : 5/7 = 12/5 - 12/5
x : 5/7 = 0
x = 0 x 5/7
x = 0
Bài 2 :
Ta có : 5/7 = 25/35 ; 6/7 = 30/35
Vậy 4 phân số thỏa mãn là 26/35 ; 27/35 ; 28/35 ; 29/35
12/5 - x : 5/7 = 12/5 x:5/7=12/5-12/5 x:5/7=0 x=0.5/7=0
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a. \(\frac{3}{4}\times x+\frac{5}{6}\times x-\frac{5}{2}=7\)
\(x\times\left(\frac{3}{4}+\frac{5}{6}\right)=7+\frac{5}{2}\)
\(x\times\left(\frac{9}{12}+\frac{10}{12}\right)=\frac{14}{2}+\frac{5}{2}\)
\(x\times\frac{19}{12}=\frac{19}{2}\)
\(x=\frac{19}{2}\div\frac{19}{12}\)
\(x=\frac{19}{2}\times\frac{12}{19}\)
\(x=6\)
b) \(12\times x-12\times84=0\)
\(12\times x=12\times84\)
\(x=84\)
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\(x+\frac{5}{6}=4\cdot\frac{5}{12}\) \(x\cdot\frac{5}{4}=2-\frac{4}{7}\)
\(x+\frac{5}{6}=\frac{5}{3}\) \(x\cdot\frac{5}{4}=\frac{10}{7}\)
\(x=\frac{5}{3}-\frac{5}{6}\) \(x=\frac{10}{7}:\frac{5}{4}\)
\(x=\frac{5}{6}\) \(x=\frac{8}{7}\)
a) X + 5/6 = 4 x 5/12
X + 5/6 = 5/3
X = 5/3 - 5/6
X = 5/6
X x 5/4 = 2 - 4/7
X x 5/4 = 10/7
X = 10/7 : 5/4
X = 10/7 x 4/5
X = 8/7
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a) = 17/19 - 17/19 + 27/35 + 35/35 = 0 + 62/35
b) = 1/3 x 4/5 + 1/3 x6/5 + 1/3 x 2 = 1/3(4/5 + 6/5 + 2) = 1/3 x 4 = = 4/3
c) 4/7 x 2/9 + 4/7 x 7/9 + 2/3 = 4/7 x (2/9 + 7/9) + 2/3 = 4/7 x 1 + 2/3 = 26/21
A) 17/19 - 17/19 + 27/35 + 35/35 = 0 + 62/35
B) 1/3 x 4/5 + 1/3 x 6/5 + 1/3 x 2 = 1/3 x(4/5 + 6/5 x 2 ) = 1/3 x 4 = 4/3
c) TƯƠNG TỰ CÂU A VÀ B
* HOKTOT*
NHA
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a. 5/12+(7/59+7/12)
=5/12+497/708
=66/59
b.(7/30+5/16)+(1/16-7/30)
=131/240+(-41/240)
=3/8
a) \(\frac{5}{12}+\left(\frac{7}{59}+\frac{7}{12}\right)\)
\(=\frac{5}{12}+\frac{7}{59}+\frac{7}{12}\)
\(=\left(\frac{5}{12}+\frac{7}{12}\right)+\frac{7}{59}\)
\(=1\frac{7}{59}\)
b) \(\left(\frac{7}{30}+\frac{5}{16}\right)+\left(\frac{1}{16}-\frac{7}{30}\right)\)
\(=\frac{7}{30}+\frac{5}{16}+\frac{1}{16}-\frac{7}{30}\)
\(=\frac{6}{16}=\frac{3}{8}\)
c) \(\frac{3}{5.9}+\frac{3}{9.13}+\frac{3}{13.17}+...+\frac{3}{2013.2017}\)
\(=\frac{3}{4}\left(\frac{1}{5}-\frac{1}{9}+\frac{1}{9}-\frac{1}{13}+\frac{1}{13}-\frac{1}{17}+...+\frac{1}{2013}-\frac{1}{2017}\right)\)
\(=\frac{3}{4}\left(\frac{1}{5}-\frac{1}{2017}\right)\)
\(=\frac{1509}{10085}\)
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\(x+\frac{5}{6}=4.\frac{5}{12}\)
=>\(x+\frac{5}{6}=\frac{5}{3}\)
=>\(x=\frac{5}{3}-\frac{5}{6}\)
=>\(x=\frac{5}{6}\)
\(x.\frac{5}{4}=2-\frac{4}{7}\)
=>\(x.\frac{5}{4}=\frac{10}{7}\)
=>\(x=\frac{10}{7}:\frac{5}{4}\)
=>\(x=\frac{8}{7}\)
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(5 2/5x7 7/12)x(13 8/9:7 5/23)
=(27/5x91/12)x(125/9:166/23)
=819/20x2875/1494
=52325/664
\(\left(\frac{12}{5}-x\right):\frac{5}{7}=\frac{12}{5}\)
\(\frac{12}{5}-x=\frac{12}{5}x\frac{5}{7}\)
\(\frac{12}{5}-x=\frac{12}{7}\)
\(x=\frac{12}{5}-\frac{12}{7}\)
\(x=\frac{24}{35}\)
\(\left(\frac{12}{5}-x\right):\frac{5}{7}=\frac{12}{5}\)
\(\frac{12}{5}-x=\frac{12}{5}\times\frac{5}{7}\)
\(\frac{12}{5}-x=\frac{12}{7}\)
\(x=\frac{12}{5}-\frac{12}{7}\)
\(x=\frac{24}{35}\)
k mk nha