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19 tháng 6 2017

Để : \(\left(2x+\frac{1}{8}\right)\left(3x-\frac{4}{5}\right)>0\)

\(\Leftrightarrow\orbr{\begin{cases}2x+\frac{1}{8}>0;3x-\frac{4}{5}>0\\2x+\frac{1}{8}< 0;3x-\frac{4}{5}< 0\end{cases}}\)

\(\Leftrightarrow\orbr{\begin{cases}2x>-\frac{1}{8};3x>\frac{4}{5}\\2x< \frac{-1}{8};3x< \frac{4}{5}\end{cases}}\)

\(\Leftrightarrow\orbr{\begin{cases}x>-\frac{1}{4};x>\frac{12}{5}\Rightarrow x>\frac{12}{5}\\x< -\frac{1}{4};x< \frac{12}{5}\Rightarrow x< -\frac{1}{4}\end{cases}}\)

b) \(\left(5x-1\right)\left(2x-\frac{1}{3}\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}5x-1=0\\2x-\frac{1}{3}=0\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}5x=1\\2x=\frac{1}{3}\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=\frac{1}{5}\\x=\frac{1}{6}\end{matrix}\right.\)

16 tháng 10 2019

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

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

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

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

\(\Leftrightarrow\left[{}\begin{matrix}x=\frac{7}{15}\\x=1,05\end{matrix}\right.\)

Vậy ....

16 tháng 8 2019

1a) \(\left|\frac{3}{2}x+\frac{1}{2}\right|=\left|4x-1\right|\)

=> \(\orbr{\begin{cases}\frac{3}{2}x+\frac{1}{2}=4x-1\\\frac{3}{2}x+\frac{1}{2}=1-4x\end{cases}}\)

=> \(\orbr{\begin{cases}-\frac{5}{2}x=-\frac{3}{2}\\\frac{11}{2}x=\frac{1}{2}\end{cases}}\)

=> \(\orbr{\begin{cases}x=\frac{5}{3}\\x=\frac{1}{11}\end{cases}}\)

b) \(\left|\frac{5}{4}x-\frac{7}{2}\right|-\left|\frac{5}{8}x+\frac{3}{5}\right|=0\)

=>\(\left|\frac{5}{4}x-\frac{7}{2}\right|=\left|\frac{5}{8}x+\frac{3}{5}\right|\)

=> \(\orbr{\begin{cases}\frac{5}{4}x-\frac{7}{2}=\frac{5}{8}x+\frac{3}{5}\\\frac{5}{4}x-\frac{7}{2}=-\frac{5}{8}x-\frac{3}{5}\end{cases}}\)

=> \(\orbr{\begin{cases}\frac{5}{8}x=\frac{41}{10}\\\frac{15}{8}x=\frac{29}{10}\end{cases}}\)

=> \(\orbr{\begin{cases}x=\frac{164}{25}\\x=\frac{116}{75}\end{cases}}\)

c) TT

16 tháng 8 2019

a, \(\left|\frac{3}{2}x+\frac{1}{2}\right|=\left|4x-1\right|\)

=> \(\orbr{\begin{cases}\frac{3}{2}x+\frac{1}{2}=4x-1\\-\frac{3}{2}x-\frac{1}{2}=4x-1\end{cases}}\)

=> \(\orbr{\begin{cases}\frac{3}{2}x+\frac{1}{2}-4x=-1\\-\frac{3}{2}x-\frac{1}{2}-4x=-1\end{cases}}\)

=> \(\orbr{\begin{cases}x=\frac{3}{5}\\x=\frac{1}{11}\end{cases}}\)

\(b,\left|\frac{5}{4}x-\frac{7}{2}\right|-\left|\frac{5}{8}x+\frac{3}{5}\right|=0\)

=> \(\left|\frac{5}{4}x-\frac{7}{2}\right|-0=\left|\frac{5}{8}x+\frac{3}{5}\right|\)

=> \(\frac{\left|5x-14\right|}{4}=\frac{\left|25x+24\right|}{40}\)

=> \(\frac{10(\left|5x-14\right|)}{40}=\frac{\left|25x+24\right|}{40}\)

=> \(\left|50x-140\right|=\left|25x+24\right|\)

=> \(\orbr{\begin{cases}50x-140=25x+24\\-50x+140=25x+24\end{cases}}\Rightarrow\orbr{\begin{cases}x=\frac{164}{25}\\x=\frac{116}{75}\end{cases}}\)

c, \(\left|\frac{7}{5}x+\frac{2}{3}\right|=\left|\frac{4}{3}x-\frac{1}{4}\right|\)

=> \(\orbr{\begin{cases}\frac{7}{5}x+\frac{2}{3}=\frac{4}{3}x-\frac{1}{4}\\-\frac{7}{5}x-\frac{2}{3}=\frac{4}{3}x-\frac{1}{4}\end{cases}}\)

=> \(\orbr{\begin{cases}x=-\frac{55}{4}\\x=-\frac{25}{164}\end{cases}}\)

Bài 2 : a. |2x - 5| = x + 1

 TH1 : 2x - 5 = x + 1

    => 2x - 5 - x = 1

    => 2x - x - 5 = 1

    => 2x - x = 6

    => x = 6

TH2 : -2x + 5 = x + 1

   => -2x + 5 - x = 1

   => -2x - x + 5 = 1

   => -3x = -4

   => x = 4/3

Ba bài còn lại tương tự

24 tháng 9 2016

a. 6,5 -9/4:/x+1/3\=/-2\

6,5-9/4:/x+1/3\=2

9/4:/x+1/3\=6,5-2

9/4:/x+1/3\=4,5

/x+1/3\=9/4:4,5

/x+1/3\=1/2

x+1/3=1/2                hoặc           x+1/3= -1/2

x= 1/2-1/3                                    x= -1/2-1/3

x= 1/6                                          x= -5/6

Vậy x=1/6 hoặcx= -5/6

b.     2-/3/2x-1/4\ = /-5/4\

2-/3/2x-1/4\=5/4

/3/2x-1/4\=2-5/4

/3/2x-1/4\=3/4

3/2x-1/4=3/4                    hoặc         3/2x-1/4=  -3/4

3/2x=3/4+1/4                                    3/2x= -3/4+1/4

3/2x=1                                              3/2x=  -1/2

x=1:3/2                                              x=  -1/2:3/2

x=2/3                                                x=  -1/3

Vậy x=2/3 hoặc  x=   -1/3

 

 

a: Để 2x+1/5=2

thì 2x+1=10

=>2x=9

hay x=9/2

Để (2x+1)/5=-2

thì 2x+1=-10

=>2x=-11

hay x=-11/2

Để (2x+1)/5=0 thì 2x+1=0

hay x=-1/2

Để (2x+1)/5=4 thì 2x+1=20

=>2x=19

hay x=19/2

b: Để (x+1)/7=0 thì x+1=0

hay x=-1

Để (3x+3)/5=0 thì 3x+3=0

hay x=-1

9 tháng 8 2016

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

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

\(\frac{1}{3}:2x=\frac{-21}{4}\)

\(2x=\frac{1}{3}:\frac{-21}{4}\)

\(2x=\frac{-4}{63}\)

\(x=\frac{-4}{63}:2\)

\(x=\frac{-2}{63}\)

\(\)

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

\(\Rightarrow\frac{1}{3}:2x=-\frac{21}{4}\)

\(\Rightarrow2x=\frac{-4}{63}\)

\(\Rightarrow x=\frac{-2}{63}\)

\(\left(3x-\frac{1}{4}\right)\left(x+\frac{1}{2}\right)=0\)

\(\Rightarrow\orbr{\begin{cases}3x-\frac{1}{4}=0\\x+\frac{1}{2}=0\end{cases}\Rightarrow\orbr{\begin{cases}x=\frac{1}{12}\\x=\frac{-1}{2}\end{cases}}}\)

\(\left(2x-5\right)\left(\frac{3}{2}x+9\right)\left(0,3x-12\right)=0\)

Th1 : \(2x-5=0\Rightarrow x=\frac{5}{2}\)

Th2 : \(\frac{3}{2}x+9=0\Rightarrow x=-6\)

Th3 : \(0,3x-12=0\Rightarrow x=\frac{12}{0,3}\)