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a) y + 3/7 x 21/9 = 5
y + 3/7 x 7/3 = 5
y + 1 = 5
y = 4
b) y x 3/5 - 1/2 = 4/5
y x 3/5 = 4/5 + 1/2
y x 3/5 = 13/10
y = 13/6
c) 9/8 - y + 2/5 = 1/4
y - 2/5 = 9 /8 - 1/4
y - 2/5 = 7/8
y = 51/40
d) y - 6/5 : 2/3 = 5/6
y - 9/5 = 5/6
y = 79/30
e) y : 7/8 + 3/4 = 7/4
y : 7/8 = 1
y = 7/8
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ta có : \(\left(\frac{1}{2}+\frac{3}{2}\right)+\left(\frac{3}{7}+\frac{11}{7}\right)+\left(\frac{1}{5}+\frac{4}{5}\right)\)
= \(\frac{4}{2}+\frac{14}{7}+\frac{5}{5}=2+2+1\)
\(=5\)
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\(y+\frac{3}{4}=\frac{4}{5}\)
\(y=\frac{4}{5}-\frac{3}{4}\)
\(y=\frac{1}{20}\)
Vậy y = 1/20
\(y-\frac{3}{11}=\frac{9}{22}\)
\(y=\frac{9}{22}+\frac{3}{11}\)
\(y=\frac{15}{22}\)
Vậy y = 15/22
\(\frac{9}{2}-y=\frac{2}{9}\)
\(y=\frac{9}{2}-\frac{2}{9}\)
\(y=\frac{77}{18}\)
Vậy y = 77/18
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\(\frac{2}{5}\times\frac{3}{8}+\frac{3}{4}=\frac{2\times3}{5\times8}+\frac{3}{4}=\frac{1\times3}{5\times4}+\frac{3}{4}=\frac{3}{20}+\frac{3}{4}=\frac{3}{20}+\frac{15}{20}=\frac{18}{20}=\frac{9}{10}\)
\(\frac{2}{5}+\frac{3}{8}\times\frac{3}{4}=\frac{2}{5}+\frac{9}{32}=\frac{64}{160}+\frac{45}{160}=\frac{109}{160}\)
Hai bài kia tương tự
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3/5 + 4 : 2/3 - 3/2
= 3/5 + 4 x 3/2 - 3/2
= 3/5 + 6 - 3/2
= 3/5 + 30/5 - 3/2
= 33/5 - 3/2
= 66/10 - 15/10
= 51/10
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Bài làm :
\(a,\frac{1}{7}+\frac{3}{4}+\frac{2}{7}+\frac{4}{7}\)
\(=\left(\frac{1}{7}+\frac{2}{7}+\frac{4}{7}\right)+\frac{3}{4}\)
\(=1+\frac{3}{4}\)
\(=\frac{7}{4}\)
\(b,\frac{4}{7}:\frac{2}{5}+\frac{3}{7}:\frac{2}{5}-\frac{7}{9}\)
\(=\left(\frac{4}{7}+\frac{3}{7}\right):\frac{2}{5}-\frac{7}{9}\)
\(=1:\frac{2}{5}-\frac{7}{9}\)
\(=\frac{5}{2}-\frac{7}{9}\)
\(=\frac{31}{18}\)
Học tốt
\(a,\frac{1}{7}+\frac{3}{4}+\frac{2}{7}+\frac{4}{7}\)
\(=\left(\frac{1}{7}+\frac{2}{7}+\frac{4}{7}\right)+\frac{3}{4}\)
\(=1+\frac{3}{4}\)
\(=\frac{7}{4}\)
\(b,\frac{4}{7}:\frac{2}{5}+\frac{3}{7}:\frac{2}{5}-\frac{7}{9}\)
\(=\left(\frac{4}{7}+\frac{3}{7}\right):\frac{2}{5}-\frac{7}{9}\)
\(=1:\frac{2}{5}-\frac{7}{9}\)
\(=\frac{5}{2}-\frac{7}{9}\)
\(=\frac{31}{18}\)
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2 : 3 = \(\frac{2}{3}\)
4 : 5 =\(\frac{4}{5}\)
6 : 7 = \(\frac{6}{7}\)
Học tốt !
bằng 3/5 nhé
Học tốt
24/40