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b: \(\dfrac{5}{7}-\dfrac{2}{3}\cdot x=\dfrac{4}{5}\)
=>\(\dfrac{2}{3}x=\dfrac{5}{7}-\dfrac{4}{5}=\dfrac{25-28}{35}=\dfrac{-3}{35}\)
=>\(x=-\dfrac{3}{35}:\dfrac{2}{3}=\dfrac{-3}{35}\cdot\dfrac{3}{2}=-\dfrac{9}{70}\)
c: \(\dfrac{1}{2}x+\dfrac{3}{5}x=-\dfrac{2}{3}\)
=>\(x\left(\dfrac{1}{2}+\dfrac{3}{5}\right)=-\dfrac{2}{3}\)
=>\(x\cdot\dfrac{5+6}{10}=\dfrac{-2}{3}\)
=>\(x\cdot\dfrac{11}{10}=-\dfrac{2}{3}\)
=>\(x=-\dfrac{2}{3}:\dfrac{11}{10}=-\dfrac{2}{3}\cdot\dfrac{10}{11}=\dfrac{-20}{33}\)
d: \(\dfrac{4}{7}\cdot x-x=-\dfrac{9}{14}\)
=>\(\dfrac{-3}{7}\cdot x=\dfrac{-9}{14}\)
=>\(\dfrac{3}{7}\cdot x=\dfrac{9}{14}\)
=>\(x=\dfrac{9}{14}:\dfrac{3}{7}=\dfrac{9}{14}\cdot\dfrac{7}{3}=\dfrac{3}{2}\)
a, 7\(x\) - \(x\) = 521 : 519 + 3.22.7
6\(x\) = 53 + 3.4.7
6\(x\) = 125 + 12.7
6\(x\) = 125 + 84
6\(x\) = 209
\(x\) = 209 : 6
\(x\) = \(\dfrac{209}{6}\)
b; 11\(x\) - 7\(x\) + 34 : 33 = 54 + 2\(x\)
4\(x\) + 3 = 625 + 2\(x\)
4\(x\) - 2\(x\) = 625 - 3
2\(x\) = 622
\(x\) = 622 : 2
\(x\) = 311
c; 75 - 5.(\(x-3\))3 = 700
5.(\(x\) - 3)3 = 700 - 75
5.(\(x\) - 3)3 = - 625
(\(x\) - 30)3 = - 625 : 5
(\(x\) - 30)3 = - 125
(\(x-3\))3 = (-5)3
\(x\) - 3 = - 5
\(x\) = - 5 + 3
\(x\) = -2
d, 3.(2\(x\) - 1)2 = 75
(2\(x\) - 1)2 = 75 : 3
(2\(x\) - 1)2 = 25
\(\left[{}\begin{matrix}2x-1=-5\\2x-1=5\end{matrix}\right.\)
\(\left[{}\begin{matrix}2x=-5+1\\2x=5+1\end{matrix}\right.\)
\(\left[{}\begin{matrix}2x=-4\\2x=6\end{matrix}\right.\)
\(\left[{}\begin{matrix}x=-2\\x=3\end{matrix}\right.\)
do các phân số ở hàng số thứ 2 đã tối giản nên x=0=>7x=0 =>tổng các phân số sau đều tối giản
a: =>x/27+1=-2/3
=>x/27=-5/3
=>x=-45
b: \(\Leftrightarrow x-4=\dfrac{2}{5}:\dfrac{20}{21}=\dfrac{2}{5}\cdot\dfrac{21}{20}=\dfrac{42}{100}=\dfrac{21}{50}\)
=>x=221/50
c: \(\Leftrightarrow x+\dfrac{2}{3}=\dfrac{4}{60}=\dfrac{1}{15}\)
=>x=1/15-2/3=1/15-10/15=-9/15=-3/5
d: \(\Leftrightarrow x\cdot\dfrac{3}{5}=\dfrac{1}{5}-\dfrac{15}{14}\cdot\dfrac{21}{20}\)
=>\(x\cdot\dfrac{3}{5}=\dfrac{1}{5}-\dfrac{3}{2}\cdot\dfrac{3}{4}=\dfrac{1}{5}-\dfrac{9}{8}=\dfrac{-37}{40}\)
=>x=-37/24
e: =>-3/7x=84/45
=>x=-196/45
f: =>11/10x=-2/3
=>x=-20/33
a) (x + 5/6) . 12/5 - 5/4 = 35%
=> (x + 5/6) . 12/5 = 7/20 + 5/4
=> (x + 5/6) . 12/5 = 8/5
=> x + 5/6 = 8/5 : 12/5
=> x + 5/6 = 2/3
=> x = 2/3 - 5/6
=> x = -1/6
b) 3.(x - 1/2) - 5.(x + 3/5) = -x + 1/5
=> 3x - 3/2 - 5x - 3 = -x + 1/5
=> -2x - 9/2 = -x + 1/5
=> -2x + x = 1/5 + 9/2
=> -x = 47/10
=> x = -47/10
c) 5/2 - 3.(1/3 - x) = 1/4 - 7x
=> 5/2 - 1 + 3x = 1/4 - 7x
=> 3/2 + 3x = 1/4 - 7x
=> 3/x + 7x = 1/4 - 3/2
=> 10x = -5/4
=> x = -5/4 : 10
=> x = -1/8
d) 1/2x + 4/5 .(5/2 + x) = 15/4
=> 1/2x + 2 + 4/5x = 15/4
=> 13/10x = 15/4 - 2
=> 13/10x = 7/4
=> x = 7/4 : 13/10
=> x= 35/26
a. \(\frac{1}{3}x-\frac{2}{5}=\frac{2}{3}x+1\)
\(\Leftrightarrow\frac{1}{3}x-\frac{2}{3}x=1+\frac{2}{5}\)
\(\Leftrightarrow-\frac{1}{3}x=\frac{7}{5}\)
\(\Leftrightarrow x=\frac{7}{5}\div\frac{-1}{3}\)
\(\Leftrightarrow x=\frac{21}{-5}\)
b. \(\frac{-4}{5}x+\frac{1}{3}=\frac{2}{3}x+\frac{1}{2}\)
\(\Leftrightarrow\frac{1}{3}-\frac{1}{2}=\frac{2}{3}x+\frac{4}{5}x\)
\(\Leftrightarrow\frac{-1}{6}=\frac{22}{15}x\)
\(\Leftrightarrow x=\frac{-1}{6}\div\frac{22}{15}\)
\(\Leftrightarrow x=\frac{-15}{132}\)
\(\frac{5}{2}-3.\left(\frac{1}{3}-x\right)=\frac{1}{4}-7x\)
\(\frac{5}{2}-1+3x=\frac{1}{4}-7x\)
\(3x+7x=\frac{1}{4}-\frac{5}{2}+1\)
\(10x=\frac{-5}{4}\)
\(x=\frac{-1}{8}\)
Vậy...
\(\frac{5}{2}-3\times\left(\frac{1}{3}-x\right)=\frac{1}{4}-7x\)
\(\frac{5}{2}-1+3x=\frac{1}{4}-7x\)
\(3x+7x=\frac{1}{4}-\frac{5}{2}+1\)
\(10x=\frac{-5}{4}\)
\(x=\frac{-5}{4}\div10\)
\(x=\frac{-1}{8}\)