đg cần gấp

\(2.8:\left(\frac{1}{5}-3x\right)=1\frac{2}{5}\)

\(\frac{14}{5}:\left(\frac{1}{5}-3x\right)=\frac{7}{5}\)

\(\frac{1}{5}-3x=\frac{14}{5}:\frac{7}{5}\)

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

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

\(3x=-\frac{9}{5}\)

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

\(2,8:\left(\frac{1}{5}-3x\right)=1\frac{2}{5}\Rightarrow\frac{14}{5}:\left(\frac{1}{5}-3x\right)=\frac{7}{5}\)

\(\Rightarrow\frac{1}{5}-3x=\frac{14}{5}:\frac{7}{5}\)

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

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

\(\Rightarrow3x=-\frac{9}{5}\)

\(\Rightarrow x=-\frac{9}{5}:3=-\frac{3}{5}\)

\(2,8:\left(3.x-\frac{5}{8}\right)=2\frac{2}{5}\)

=>\(\frac{14}{5}:\left(3.x-\frac{5}{8}\right)=\frac{12}{5}\)

=>\(\frac{14}{5}:\frac{13}{5}=3.x-\frac{5}{8}\)

=>\(3.x-\frac{5}{8}=\frac{14}{13}\)

=>\(3.x=\frac{14}{13}+\frac{5}{8}\)

=>\(3.x=\frac{177}{104}\)

=>\(x=\frac{59}{104}\)

2,8 :( 3x -5/8)= 2/2/5

2,8:( 3x- 5,8)= 12/5

3x-5/8         = 2,8:12/5

3x -5/8        = 7/6

3x= 7/6 +5/8

3x= 43/ 24

x= 43/24 :3

x= 43/72

nha bn, mknghix vậy

\(2,8:\left(3x-\frac{5}{8}\right)=2\frac{2}{5}\)

\(\frac{14}{5}:\left(3x-\frac{5}{8}\right)=\frac{12}{5}\)

        \(\left(3x-\frac{5}{8}\right)\)\(=\frac{14}{5}:\frac{12}{5}\)

         \(\left(3x-\frac{5}{8}\right)\)\(=\frac{14}{5}.\frac{5}{12}\)

           \(3x-\frac{5}{8}\)   \(=\frac{7}{6}\)

          \(3x\)              \(=\frac{7}{6}+\frac{5}{8}\)

          \(3x\)               \(=\frac{28}{24}+\frac{15}{24}\)

          \(3x\)               \(=\frac{43}{24}\)

           \(x\)                \(=\frac{43}{24}:3\)

          \(x\)                  \(=\frac{43}{24}.\frac{1}{3}\)

         \(x\)                    \(=\frac{43}{72}\)

Vậy   \(x\)                     \(=\frac{43}{72}\)

CHÚC BẠN HỌC TỐT

a) -0,6 . x - 7/3 = 5,4 (sửa dấu phẩy thành dấu nhân)

=> \(-\frac{3}{5}x-\frac{7}{3}=\frac{27}{5}\)

=> \(-\frac{3}{5}x=\frac{27}{5}+\frac{7}{3}=\frac{116}{15}\)

=> \(x=\frac{116}{15}:\left(-\frac{3}{5}\right)=\frac{116}{15}\cdot\left(-\frac{5}{3}\right)=-\frac{116}{9}\)

b) 2,8 : \(\left(\frac{1}{5}-3x\right)=1\frac{2}{5}\)

=> \(\frac{1}{5}-3x=2,8:1\frac{2}{5}\)

=> \(\frac{1}{5}-3x=\frac{14}{5}:\frac{7}{5}=\frac{14}{5}\cdot\frac{5}{7}=2\)

=> 3x = \(\frac{1}{5}-2=-\frac{9}{5}\)

=> \(x=\left(-\frac{9}{5}\right):3=\left(-\frac{9}{5}\right)\cdot\frac{1}{3}=-\frac{3}{5}\)

Nên sửa lại đề câu a đi nhá :)) 

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

Đặt \(a=\left|3x-\frac{1}{5}\right|\) ta đc:

\(\frac{1}{5}-\frac{5}{2}a=\frac{2}{3}a-\frac{2}{3}\)

\(\Leftrightarrow-\frac{5}{2}a=\frac{2}{3}a-\frac{13}{15}\)

\(\Leftrightarrow-\frac{5a}{2}=\frac{10a}{15}-\frac{13}{15}\)

\(\Leftrightarrow-\frac{5a}{2}=\frac{10a-13}{15}\Rightarrow-5a\cdot15=2\left(10a-13\right)\)

\(\Leftrightarrow-75a=20a-26\)

\(\Leftrightarrow-95a=-26\Leftrightarrow a=\frac{26}{95}\)

\(\Leftrightarrow\left|3x-\frac{1}{5}\right|=\frac{26}{95}\)

\(\Leftrightarrow\left[\begin{array}{nghiempt}3x-\frac{1}{5}=\frac{26}{95}\\3x-\frac{1}{5}=-\frac{26}{95}\end{array}\right.\)

\(\Leftrightarrow\left[\begin{array}{nghiempt}3x=\frac{9}{19}\\3x=-\frac{7}{95}\end{array}\right.\)

\(\Leftrightarrow\left[\begin{array}{nghiempt}x=\frac{3}{19}\\x=-\frac{7}{285}\end{array}\right.\)

Sao k ai giúp vậy

\(2,8:\left(\frac{1}{5}-3x\right)=1\frac{2}{5}\)

\(\frac{14}{5}:\left(\frac{1}{5}-3x\right)=\frac{7}{5}\)

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

\(3x=\frac{-9}{10}\)

\(x=\frac{-3}{10}\)

Vậy \(x=\frac{-3}{10}\)

\(2,8:\left(\frac{1}{5}-3x\right)=1\frac{2}{5}\)

\(\frac{1}{5}-3x=\frac{28}{10}:\frac{7}{5}\)

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

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

\(3x=\frac{-9}{5}\)

\(x=\frac{-9}{5}:3\)

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

\(\frac{14}{5}:\left(\frac{1}{5}-3x\right)=\frac{12}{5}\)

\(\Rightarrow\)\(\frac{1}{5}-3x=\frac{7}{6}\)

\(\Rightarrow\)

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

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

cho mình

a) \(\left|2x\right|-\left|-2,5\right|=\left|-7,5\right|\)

\(\Leftrightarrow\left|2x\right|-2,5=7,5\)

\(\Leftrightarrow\left|2x\right|=10\)            

\(\Leftrightarrow\begin{cases}x\ge0\\2x=10\end{cases}\) hoặc \(\begin{cases}x< 0\\2x=-10\end{cases}\)

\(\Leftrightarrow\begin{cases}x\ge0\\x=5\left(tm\right)\end{cases}\) hoặc \(\begin{cases}x< 0\\x=-5\left(tm\right)\end{cases}\)

Vậy x={5;-5}

b)\(\left|3x\right|\cdot\left|-3,5\right|=\left|-2,8\right|\)

\(\Leftrightarrow\left|3x\right|\cdot3,5=2,8\)

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

\(\Leftrightarrow\begin{cases}x\ge0\\3x=\frac{4}{5}\end{cases}\) hoặc \(\begin{cases}x< 0\\3x=-\frac{4}{5}\end{cases}\)

\(\Leftrightarrow\begin{cases}x\ge0\\x=\frac{4}{15}\end{cases}\) hoặc \(\begin{cases}x< 0\\x=-\frac{4}{15}\end{cases}\)

Vậy x={4/15;-4/15}

c) \(\left(3x-5\right)\left(\frac{3}{2}x+2\right)\left(0,5x-10\right)=0\)

\(\Leftrightarrow\left[\begin{array}{nghiempt}3x-5=0\\\frac{3}{2}x+2=0\\0,5x-10=0\end{array}\right.\)\(\Leftrightarrow\left[\begin{array}{nghiempt}x=\frac{5}{3}\\x=-\frac{4}{3}\\x=20\end{array}\right.\)

a)|2x|-|-2,5|=|-7,5|

   |2x|-2,5=7,5

    |2x|=10

\(\Rightarrow\left[\begin{array}{nghiempt}2x=10\\2x=-10\end{array}\right.\)\(\Rightarrow\left[\begin{array}{nghiempt}x=5\\x=-5\end{array}\right.\)

                 Vậy x=5;-5

b)|3x|.|-3,5|=|-2,8|

    |3x|.3,5=2,8

    |3x|=0,8

\(\Rightarrow\left[\begin{array}{nghiempt}3x=0,8\\3x=-0,8\end{array}\right.\)\(\Rightarrow\left[\begin{array}{nghiempt}x=\frac{4}{15}\\x=-\frac{4}{15}\end{array}\right.\)

                 Vậy \(x=\frac{4}{15};-\frac{4}{15}\)

c, ( 3x - 5 ) . ( \(\frac{3}{2}x\) + 2 ) . ( 0,5x - 10 ) = 0 

    \(\left(3x^2+6x-\frac{15}{2}x-10\right)\left(0,5x-10\right)=0\)

      \(\left(3x^2-\frac{3}{2}x-10\right)\left(0,5x-10\right)=0\)

     \(1,5x^3-0,75x^2-5x-30x^2+15x+100=0\)

     \(1,5x^3-30,75x^2+10x+100=0\)

      \(1,5x^3-1,5x^2.20,5+10x+100=0\)

     \(1,5x^2.\left(x-20,5\right)+10.\left(x+10\right)=0\)

Đến đây thì mk .......

a) x = \(\frac{1}{3}\)

b) x =  \(\frac{1}{42}\)

1/3 và 1/42 nha bn

bn nào giải thích hộ mk với

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

<=> 2(3x-5) = 5(x+4)

<=> 6x-10 = 5x+20

<=> x = 30

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

<=> 7(3x-1) = 3(2x+1)

<=> 21x-7 = 6x+3

<=>15x = 10

<=> x = \(\frac{2}{3}\)

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

(3x - 1) . 7 = (2x + 1) . 3

21x - 7 = 6x + 3

21x - 6x = 3 + 7

15x = 10

=> x = \(\frac{2}{3}\)