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a) x = 4/5 : 5/7
x = 28/25
b) 3/5 : x = 5/6 - 2/5
3/5 : x = 13/30
x = 3/5 : 13/30
x = 18/13
a) \(\dfrac{5}{7}\times\dfrac{5}{9}+\dfrac{4}{9}\times\dfrac{5}{7}\)
\(=\dfrac{5}{7}\times\left(\dfrac{4}{9}+\dfrac{5}{9}\right)\)
\(=\dfrac{5}{7}\times1\)
\(=\dfrac{5}{7}\)
b) \(\dfrac{1}{10}+\dfrac{5}{9}+\dfrac{4}{9}+\dfrac{9}{10}-1\)
\(=\left(\dfrac{5}{9}+\dfrac{4}{9}\right)+\left(\dfrac{1}{10}+\dfrac{9}{10}-1\right)\)
\(=1+0\)
\(=1\)
c) \(\dfrac{5}{7}\times\dfrac{5}{9}+\dfrac{4}{9}\times\dfrac{5}{7}+\dfrac{2}{7}\)
\(=\dfrac{5}{7}\times\left(\dfrac{5}{9}+\dfrac{4}{9}\right)+\dfrac{2}{7}\)
\(=\dfrac{5}{7}+\dfrac{2}{7}\)
\(=1\)
d) \(\dfrac{2}{7}+\dfrac{2}{8}+\dfrac{1}{4}+\dfrac{1}{7}+\dfrac{4}{7}\)
\(=\left(\dfrac{2}{8}+\dfrac{1}{4}\right)+\left(\dfrac{2}{7}+\dfrac{1}{7}+\dfrac{4}{7}\right)\)
\(=\left(\dfrac{1}{4}+\dfrac{1}{4}\right)+1\)
\(=\dfrac{1}{2}+1\)
\(=\dfrac{3}{2}\)
e) \(\dfrac{4}{5}+\dfrac{3}{10}+\dfrac{2}{10}+0,7\)
\(=\dfrac{4}{5}+\dfrac{5}{10}+\dfrac{7}{10}\)
\(=\dfrac{4}{5}+\dfrac{12}{10}\)
\(=\dfrac{4}{5}+\dfrac{6}{5}\)
\(=\dfrac{10}{5}\)
\(=2\)
g) \(362\times728+326\times272\)
\(=326\times\left(728+272\right)\)
\(=326\times1000\)
\(=326000\)
Bài 1:
a) \(2\)\(\dfrac{2}{3}\)\(=\dfrac{8}{3}\)
b) \(1\)\(\dfrac{5}{7}=\dfrac{12}{7}\)
Viết cái đề cho rõ ràng dùm cái, mk đọc ko có hỉu j hết
\(3-\left(2x+\frac{1}{2}\right)\div\frac{1}{2}=2\)
\(\Leftrightarrow\left(2x+\frac{1}{2}\right)\div\frac{1}{2}=3-2\)
\(\Leftrightarrow\left(2x+\frac{1}{2}\right)\times2=1\)
\(\Leftrightarrow2x+\frac{1}{2}=\frac{1}{2}\)
\(\Leftrightarrow2x=\frac{1}{2}-\frac{1}{2}\)
\(\Leftrightarrow2x=0\)
\(\Leftrightarrow x=0\div2\)
\(\Leftrightarrow x=0\)
Vậy x = 0
\(3-\left(x\times2+\frac{1}{2}\right):\frac{1}{2}=2\)
\(\left(x\times2+\frac{1}{2}\right):\frac{1}{2}=3-2\)
\(\left(x\times2+\frac{1}{2}\right):\frac{1}{2}=1\)
\(x\times2+\frac{1}{2}=1\times\frac{1}{2}\)
\(x\times2+\frac{1}{2}=\frac{1}{2}\)
\(x\times2=\frac{1}{2}-\frac{1}{2}\)
\(x\times2=0\)
x = 0 : 2
x = 0
Vậy x = 0
X x 3/5 + X x 2/7 = 31/70
=> X x (3/5+2/7) = 31/70
=> X x 31/35 = 31/70
=> X = 31/70 : 31/35
=> X = 31/70 x 35/31
=> X = 1/2
X x 3/5 + X x 2/7 = 31/70
X x [ 3/5 + 2/7 ] = 31/70
X x 31/35 = 31/70
X = 31/70 : 31/35
X= 1/2
a) \(\dfrac{1}{9}\times\dfrac{4}{7}+\dfrac{1}{9}\times\dfrac{3}{7}=\dfrac{1}{9}\times\left(\dfrac{4}{7}+\dfrac{3}{7}\right)=\dfrac{1}{9}\times1=\dfrac{1}{9}\)
b) \(\dfrac{5}{13}\times\dfrac{189}{18}-\dfrac{5}{13}\times\dfrac{9}{18}=\dfrac{5}{13}\times\left(\dfrac{189}{18}-\dfrac{9}{18}\right)=\dfrac{5}{13}\times\dfrac{180}{18}=\dfrac{5}{13}\times10=\dfrac{50}{13}\)
c) \(\dfrac{12}{7}:\dfrac{4}{9}+\dfrac{4}{7}:\dfrac{4}{9}=\dfrac{12}{7}\times\dfrac{9}{4}+\dfrac{4}{7}\times\dfrac{9}{4}=\left(\dfrac{12}{7}+\dfrac{4}{7}\right)\times\dfrac{9}{4}=\dfrac{16}{7}\times\dfrac{9}{4}=\dfrac{144}{28}=\dfrac{36}{7}\)
a) 4/7 x X = 1/5 + 2/3
=> 4/7 x X = 3/15 + 10/15
=> 4/7 x X = 13/15
=> X = 13/15 : 4/7
=> X = 13/15 x 4/7 = 52/105
a ) 4 / 7 x X = 1 / 5 + 2 / 3
= > 4 / 7 x X = 3 / 1 5 + 1 0 / 1 5
= > 4 / 7 x X = 1 3 / 1 5
= > X = 1 3 / 1 5 : 4 / 7
= > X = 1 3 / 1 5 x 4 / 7
= 5 2 / 1 0 5
Ai nhanh sẽ được K
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