Tìm x trong tỉ lệ thức:
a) \(3\frac{4}{5}:40\frac{8}{15}=0,25:x\)
b) \(\frac{5}{6}:x=20:3\)
c) \(x:2,5=0,003:0,75\)
d) \(\frac{2}{3}:0,4=x:\frac{4}{5}\)
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NT
3
26 tháng 8 2018
a) x : 2,5 = 1/100
x = 1/250 * 2,5
x= 1/100
b) 5/3= x : 4/5
x= 4/5 * 5/3
x= 4/3
5 tháng 7 2019
a) \(x\div2.5=0.003\div0.75\)
\(x\div2.5=0.004\)
\(x=0.004×2.5\)
\(x=0.01\)
Vậy, \(x=0.01\)
b) \(\frac{2}{3}\div0.4=x\div\frac{4}{5}\)
\(x\div\frac{4}{5}=\frac{5}{3}\)
\(x=\frac{5}{3}×\frac{4}{5}\)
\(x=\frac{20}{15}=\frac{4}{3}\)
Vậy, \(x=\frac{4}{3}\)
Cbht
10 tháng 7 2016
1) a) Ta có: \(\frac{x}{-15}=\frac{-60}{x}\) \(\Rightarrow x^2=\left(-15\right).\left(-60\right)=900\)
\(\Rightarrow x=30\)
b) \(\frac{-2}{x}=\frac{-x}{\frac{8}{25}}\) \(\Rightarrow x.\left(-x\right)=\left(-2\right).\frac{8}{25}\)
\(\Rightarrow x.\left(-x\right)=\frac{-16}{25}\)
\(\Rightarrow x.\left(-x\right)=\left(\frac{-4}{5}\right).\frac{4}{5}\)
Vậy \(x=\frac{4}{5}\)
2) a) \(3,8: \left(2x\right)=\frac{1}{4}:2\frac{2}{3}\)
\(\Rightarrow3,8: \left(2x\right)=\frac{3}{32}\)
\(\Rightarrow2x=\frac{3}{32}:3,8=\frac{15}{608}\)
\(x=\frac{15}{608}:2=\frac{15}{1216}\)
Vậy \(x=\frac{15}{1216}\)
b) \(\left(0,25x\right):3=\frac{5}{6}:0,125\)
\(\Rightarrow\left(0,25x\right):3=\frac{20}{3}\)
\(\Rightarrow0,25x=\frac{20}{3}.3=20\)
\(\Rightarrow x=20:0,25=80\)
Vậy x = 80
c) \(0,01:2,5=\left(0,75x\right):0,75\)
\(\Rightarrow\frac{1}{250}=\left(0,75x\right):0,75\)
\(\Leftrightarrow0,75x=\frac{1}{250}.0,75=\frac{3}{1000}\)
\(\Rightarrow x=\frac{3}{1000}:0,75=\frac{1}{250}\)
Vậy \(x=\frac{1}{250}\)
d) \(1\frac{1}{3}:0,8=\frac{2}{3}:\left(0,1x\right)\)
\(\Rightarrow\frac{5}{3}=\frac{2}{3}:\left(0,1x\right)\)
\(\Rightarrow0,1x=\frac{5}{3}.\frac{2}{3}=\frac{10}{9}\)
\(\Rightarrow x=\frac{10}{9}:0,1=\frac{100}{9}\)
Vậy \(x=\frac{100}{9}\)
10 tháng 7 2016
a) \(\frac{x}{-15}=\frac{-60}{x}\Leftrightarrow x.x=-15.\left(-60\right)\Leftrightarrow x^2=900\Leftrightarrow x^2=\orbr{\begin{cases}30^2\\\left(-30\right)^2\end{cases}}\Leftrightarrow x=\orbr{\begin{cases}30\\-30\end{cases}}\)
VM
29 tháng 7 2019
a) \(x:2,4=3,5:0,7\)
=> \(x:2,4=5\)
=> \(x=5.2,4\)
=> \(x=12\)
Vậy \(x=12.\)
b) \(2\frac{1}{5}:x=-3\frac{1}{4}:\left(-2\frac{2}{5}\right)\)
=> \(\frac{11}{5}:x=-\frac{13}{4}:\left(-\frac{12}{5}\right)\)
=> \(\frac{11}{5}:x=\frac{65}{48}\)
=> \(x=\frac{11}{5}:\frac{65}{48}\)
=> \(x=\frac{528}{325}\)
Vậy \(x=\frac{528}{325}.\)
c) \(4,8:0,16=x:0,4\)
=> \(30=x:0,4\)
=> \(x=30.0,4\)
=> \(x=12\)
Vậy \(x=12.\)
Chúc bạn học tốt!
29 tháng 7 2019
\( a)x:2,4 = 3,5:0,7\\ \Leftrightarrow x:2,4 = 5\\ \Leftrightarrow x = 5 \times 2,4\\ \Leftrightarrow x = 12\\ b)2\dfrac{1}{5}:x = - 3\dfrac{1}{4}:\left( { - 2\dfrac{2}{5}} \right)\\ \Leftrightarrow \dfrac{{11}}{5}:x = \dfrac{{ - 13}}{4}:\dfrac{{ - 12}}{5}\\ \Leftrightarrow \dfrac{{11}}{5}:x = \dfrac{{65}}{{48}}\\ \Leftrightarrow x = \dfrac{{11}}{5}:\dfrac{{65}}{{48}}\\ \Leftrightarrow x = \dfrac{{528}}{{325}}\\ c)4,8:0,16 = x:0,4\\ \Leftrightarrow 30 = x:0,4\\ \Leftrightarrow x = 30 \times 0,4\\ \Leftrightarrow x = 12 \)
HQ
Hà Quang Minh
Giáo viên
19 tháng 9 2023
a)
\(\begin{array}{l}\frac{2}{9}:x + \frac{5}{6} = 0,5\\\frac{2}{9}:x = \frac{1}{2} - \frac{5}{6}\\\frac{2}{9}:x = \frac{3}{6} - \frac{5}{6}\\\frac{2}{9}:x = \frac{{ - 2}}{6}\\x = \frac{2}{9}:\frac{{ - 2}}{6}\\x = \frac{2}{9}.\frac{{ - 6}}{2}\\x = \frac{{ - 2}}{3}\end{array}\)
Vậy \(x = \frac{{ - 2}}{3}\).
b)
\(\begin{array}{l}\frac{3}{4} - \left( {x - \frac{2}{3}} \right) = 1\frac{1}{3}\\x - \frac{2}{3} = \frac{3}{4} - 1\frac{1}{3}\\x - \frac{2}{3} = \frac{3}{4} - \frac{4}{3}\\x - \frac{2}{3} = \frac{9}{{12}} - \frac{{16}}{{12}}\\x - \frac{2}{3} = \frac{{ - 7}}{{12}}\\x = \frac{{ - 7}}{{12}} + \frac{2}{3}\\x = \frac{{ - 7}}{{12}} + \frac{8}{{12}}\\x = \frac{1}{12}\end{array}\)
Vậy\(x = \frac{1}{12}\).
c)
\(\begin{array}{l}1\frac{1}{4}:\left( {x - \frac{2}{3}} \right) = 0,75\\\frac{5}{4}:\left( {x - \frac{2}{3}} \right) = \frac{3}{4}\\x - \frac{2}{3} = \frac{5}{4}:\frac{3}{4}\\x - \frac{2}{3} = \frac{5}{4}.\frac{4}{3}\\x - \frac{2}{3} = \frac{5}{3}\\x = \frac{5}{3} + \frac{2}{3}\\x = \frac{7}{3}\end{array}\)
Vậy \(x = \frac{7}{3}\).
d)
\(\begin{array}{l}\left( { - \frac{5}{6}x + \frac{5}{4}} \right):\frac{3}{2} = \frac{4}{3}\\ - \frac{5}{6}x + \frac{5}{4} = \frac{4}{3}.\frac{3}{2}\\ - \frac{5}{6}x + \frac{5}{4} = 2\\ - \frac{5}{6}x = 2 - \frac{5}{4}\\ - \frac{5}{6}x = \frac{8}{4} - \frac{5}{4}\\ - \frac{5}{6}x = \frac{3}{4}\\x = \frac{3}{4}:\left( { - \frac{5}{6}} \right)\\x = \frac{3}{4}.\frac{{ - 6}}{5}\\x = \frac{{ - 9}}{{10}}\end{array}\)
Vậy \(x = \frac{{ - 9}}{{10}}\).
a)
\(3\frac{4}{5}:40\frac{8}{15}=0,25:x\)
\(\Rightarrow\frac{19}{5}:\frac{608}{15}=\frac{1}{4}.x\)
\(\Rightarrow\frac{1}{4}.x=\frac{3}{32}\)
\(\Rightarrow x=\frac{3}{8}\)
Vậy x = 3 / 8
b) \(\frac{5}{6}:x=20:3\)
\(\Rightarrow\frac{5}{6x}=\frac{20}{3}\)
\(\Rightarrow120x=15\)
\(\Rightarrow x=\frac{1}{5}\)
Vậy x = 1 / 5
c)
\(x:2,5=0,003:0,75\)
\(\Rightarrow x.\frac{2}{5}=\frac{3}{1000}.\frac{4}{3}\)
\(\Rightarrow x.\frac{2}{5}=\frac{1}{250}\)
\(\Rightarrow x=\frac{1}{100}\)
d)
\(\frac{2}{3}:0,4=x:\frac{4}{5}\)
\(\Rightarrow\frac{2}{3}:\frac{2}{5}=\frac{5x}{4}\)
\(\Rightarrow\frac{5x}{4}=\frac{5}{3}\)
\(\Rightarrow15x=20\)
\(\Rightarrow x=\frac{4}{3}\)
Vậy x = 4 / 3
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