\(\frac{x}{3}\)=\(\frac{5}{7}\)

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18 tháng 9 2021

x = 2,(142857) = 15/7

xin tiick

18 tháng 9 2021

x=15/7

4 tháng 8 2019

a) \(\frac{1}{4}+\frac{3}{4}x=\frac{3}{4}\Leftrightarrow\frac{3}{4}x=\frac{1}{2}\Leftrightarrow x=\frac{1}{2}\times\frac{4}{3}\Leftrightarrow x=\frac{2}{3}\)

b)\(1\frac{3}{4}x+1\frac{1}{2}=-\frac{4}{5}\Leftrightarrow\frac{7}{4}x+\frac{3}{2}=-\frac{4}{5}\Leftrightarrow\frac{7}{4}x=-\frac{23}{10}\)

\(\Leftrightarrow x=-\frac{23}{10}\times\frac{4}{7}\Leftrightarrow x=-\frac{46}{35}\)

c)\(\frac{3}{4}x+\frac{2}{5}x=1,2\Leftrightarrow x\left(\frac{3}{4}+\frac{2}{5}\right)=1,2\Leftrightarrow\frac{23}{20}x=1,2\)

\(\Leftrightarrow x=1,2\times\frac{20}{23}\Leftrightarrow x=\frac{24}{23}\)

d)\(\frac{3}{7}+\frac{1}{7}:x=\frac{3}{14}\Leftrightarrow\frac{1}{7x}=\frac{3}{14}-\frac{3}{7}\Leftrightarrow\frac{1}{7x}=-\frac{3}{14}\Leftrightarrow14=-3\times7x\)

\(\Leftrightarrow-21x=14\Leftrightarrow x=-\frac{2}{3}\)

e) \(-\frac{3}{4}-\left|\frac{4}{5}-x\right|=-1\Leftrightarrow\left|\frac{4}{5}-x\right|=-\frac{3}{4}+1\Leftrightarrow\left|\frac{4}{5}-x\right|=\frac{1}{4}\)

\(\Leftrightarrow\left[{}\begin{matrix}\frac{4}{5}-x=\frac{1}{4}\\\frac{4}{5}-x=-\frac{1}{4}\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=\frac{11}{20}\\x=\frac{21}{20}\end{matrix}\right.\)

4 tháng 8 2019

a, \(\frac{1}{4}+\frac{3}{4}x=\frac{3}{4}\\ \Rightarrow\frac{3}{4}x=\frac{1}{2}\\ \Rightarrow x=\frac{2}{3}\)

Vậy \(x=\frac{2}{3}\)

b, \(1\frac{3}{4}x+1\frac{1}{2}=\frac{-4}{5}\\ \frac{7}{4}x+\frac{3}{2}=\frac{-4}{5}\\ \Rightarrow\frac{7}{4}x=\frac{-23}{10}\\ \Rightarrow x=\frac{-46}{35}\)

Vậy \(x=\frac{-46}{35}\)

c, \(\frac{3}{4}x+\frac{2}{5}x=1,2\\ x\left(\frac{3}{4}+\frac{2}{5}\right)=\frac{6}{5}\\ x\cdot\frac{23}{20}=\frac{6}{5}\\ \Rightarrow x=\frac{24}{23}\)

Vậy \(x=\frac{24}{23}\)

d, \(\frac{3}{7}+\frac{1}{7}:x=\frac{3}{14}\\ \Rightarrow\frac{1}{7}:x=\frac{-3}{14}\\ \Rightarrow x=\frac{-2}{3}\)

Vậy \(x=\frac{-2}{3}\)

e, \(\frac{-3}{4}-\left|\frac{4}{5}-x\right|=-1\\ \Rightarrow\left|\frac{4}{5}-x\right|=\frac{1}{4}\\ \Rightarrow\left[{}\begin{matrix}\frac{4}{5}-x=\frac{1}{4}\\\frac{4}{5}-x=\frac{-1}{4}\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=\frac{11}{20}\\x=\frac{21}{20}\end{matrix}\right.\)

Vậy \(x\in\left\{\frac{11}{20};\frac{21}{20}\right\}\)

10 tháng 9 2020

giúp mik vs, mik bik các pạn giờ này đang ngủ rùi nhưng giúp mik lần này thui.yêu các pạn nhìu

12 tháng 9 2020

\(5\frac{1}{2}+\left(-3\right)=\frac{11}{2}+\frac{-3}{1}\)\(=\frac{11}{2}+\frac{-6}{2}=\frac{5}{2}\)\(;\)

\(4\frac{9}{11}+\left(-2\frac{1}{11}\right)=\frac{53}{11}+\frac{-23}{11}\)\(=\frac{30}{11}\)\(;\)

\(2\frac{1}{2}+\left(-6\right)=\frac{5}{2}+\frac{-6}{1}\)\(=\frac{5}{2}+\frac{-12}{2}=\frac{-7}{2}\)\(;\)

\(\left(-\frac{4}{5}\right)+\frac{1}{2}=\frac{-4}{5}+\frac{1}{2}\)\(=\frac{-8}{10}+\frac{5}{10}=\frac{-3}{10}\)\(;\)

\(4,3-\left(-1,2\right)=4,3+1,2=5,5\)\(=\frac{55}{10}=\frac{11}{2}\)\(;\)

\(0-\left(-0,4\right)=0+0,4=0,4\)\(=\frac{4}{10}=\frac{2}{5}\)\(;\)

\(\frac{-2}{3}-\frac{-1}{3}=\frac{-2}{3}+\frac{1}{3}=\frac{-1}{3}\)\(;\)

\(\frac{-1}{2}-\frac{-1}{6}=\frac{-1}{2}+\frac{1}{6}\)\(=\frac{-3}{6}+\frac{1}{6}=\frac{-2}{6}=\frac{-1}{3}\)\(;\)

\(x+\frac{1}{3}=\frac{3}{4}\)                                \(;\)               \(x-\frac{2}{5}=\frac{5}{7}\)            \(;\)      

    \(x=\frac{3}{4}-\frac{1}{3}\)                                                             \(x=\frac{5}{7}+\frac{2}{5}\)

    \(x=\frac{5}{12}\)                                                                        \(x=\frac{39}{35}\)

\(-x-\frac{2}{3}=-\frac{6}{7}\)                                \(;\)               \(\frac{4}{7}-x=\frac{1}{3}\)

 \(\frac{6}{7}-\frac{2}{3}=x\)                                                          \(\frac{4}{7}-\frac{1}{3}=x\)

            \(\frac{4}{21}=x\) \(\Leftrightarrow\)\(x=\frac{4}{21}\)                                                       \(\frac{5}{21}=x\)\(\Leftrightarrow\)\(x=\frac{5}{12}\)

24 tháng 4 2020

1.a) Sửa lại đề: \(\frac{11}{17}\)ở mẫu chuyển thành \(\frac{11}{7}\)

\(\frac{0,75+0,6-\frac{3}{7}-\frac{3}{13}}{2,75+2,2-\frac{11}{7}-\frac{11}{13}}=\frac{\frac{3}{4}+\frac{3}{5}-\frac{3}{7}-\frac{3}{13}}{\frac{11}{4}+\frac{11}{5}-\frac{11}{7}-\frac{11}{13}}\)\(=\frac{3\left(\frac{1}{4}+\frac{1}{5}-\frac{1}{7}-\frac{1}{13}\right)}{11\left(\frac{1}{4}+\frac{1}{5}-\frac{1}{7}-\frac{1}{13}\right)}=\frac{3}{11}\)

( vì \(\frac{1}{4}+\frac{1}{5}-\frac{1}{7}-\frac{1}{13}\ne0\))

2.a) \(\frac{3}{5}+\frac{3}{2}.x=\frac{-5}{7}\)\(\Leftrightarrow\frac{3}{2}.x=\frac{-5}{7}-\frac{3}{5}\)

\(\Leftrightarrow\frac{3}{2}.x=\frac{-46}{35}\)\(\Leftrightarrow x=\frac{-46}{35}:\frac{3}{2}\)\(\Leftrightarrow x=\frac{-92}{105}\)

Vậy \(x=\frac{-92}{105}\)

b) \(\left(4x-\frac{1}{3}\right).\left(\frac{3}{2}x+\frac{5}{6}\right)=0\)\(\Leftrightarrow\orbr{\begin{cases}4x-\frac{1}{3}=0\\\frac{3}{2}x+\frac{5}{6}=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}4x=\frac{1}{3}\\\frac{3}{2}x=\frac{-5}{6}\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=\frac{1}{12}\\x=\frac{-5}{9}\end{cases}}\)

Vậy \(x=\frac{-5}{9}\)hoặc \(x=\frac{1}{12}\)

9 tháng 4 2020

a) \(\frac{21}{47}+\frac{9}{45}+\frac{26}{47}+\frac{4}{5}\)

\(=\left(\frac{21}{47}+\frac{26}{47}\right)+\left(\frac{9}{45}+\frac{4}{5}\right)\)

\(=\frac{47}{47}+\left(\frac{1}{5}+\frac{4}{5}\right)\)

\(=1+1=2\)

b) \(12.\left(-\frac{2}{3}\right)^2+\frac{4}{3}\)

\(=12.\frac{4}{9}+\frac{4}{3}\)

\(=\frac{16}{3}+\frac{4}{3}\)

\(=\frac{20}{3}\)

c) \(12,5.\left(-\frac{5}{7}\right)+15.\left(-\frac{5}{7}\right)\)

\(=\left(-\frac{5}{7}\right).\left(12,5+15\right)\)

\(=\left(-\frac{5}{7}\right).27,5\)

\(=\left(-\frac{5}{7}\right).\frac{55}{2}\)

\(=-\frac{275}{14}\)

d) \(\frac{4}{5}.\left(\frac{7}{2}+\frac{1}{4}\right)^2\)

\(=\frac{4}{5}.\left(\frac{14}{4}+\frac{1}{4}\right)^2\)

\(=\frac{4}{5}.\left(\frac{15}{4}\right)^2\)

\(=\frac{4}{5}.\frac{225}{16}\)

\(=\frac{45}{4}\)

9 tháng 4 2020

a)\(\frac{21}{47}+\frac{9}{45}+\frac{26}{47}+\frac{4}{5}\)

=\(\frac{21}{47}+\frac{1}{5}+\frac{26}{47}+\frac{4}{5}\)

=\(\left(\frac{21}{47}+\frac{26}{47}\right)+\left(\frac{1}{5}+\frac{4}{5}\right)\)

=\(\frac{47}{47}+\frac{5}{5}=1+1=2\)

b)\(12.\left(-\frac{2}{3}\right)^2+\frac{4}{3}\)

=\(12.\frac{4}{9}+\frac{4}{3}\)

=\(\frac{12}{1}.\frac{4}{9}+\frac{4}{3}=\frac{48}{9}+\frac{4}{3}\)

=\(\frac{16}{3}+\frac{4}{3}=\frac{20}{3}\)

c)\(12,5.\left(-\frac{5}{7}\right)+1,5.\left(-\frac{5}{7}\right)\)

=\(\left(-\frac{5}{7}\right).\left(12,5+1,5\right)\)

=\(\left(-\frac{5}{7}\right).14=\left(-\frac{5}{7}\right).\frac{14}{1}=-10\)

d)\(\frac{4}{5}.\left(\frac{7}{2}+\frac{1}{4}\right)^2\)

=\(\frac{4}{5}.\left(\frac{14}{4}+\frac{1}{4}\right)^2\)

=\(\frac{4}{5}.\left(\frac{15}{4}\right)^2\)

=\(\frac{4}{5}.\frac{225}{16}\)

=\(\frac{900}{80}=\frac{45}{4}\)

Nhớ tick cho mình nha!banh