a) x= \(\frac{-5}{12}\)

b) x = \(\frac{2}{5}\)

c) x =\(\frac{-87}{140}\)

d) x = \(\frac{109}{140}\)

e) x = \(\frac{13}{63}\)

Làm đầy đủ nha , mk thick cho , đừng viết kết quả 

a) \(\frac{11}{13}\)-  (\(\frac{5}{42}\)- X ) = -(\(\frac{15}{28}\)-\(\frac{11}{13}\))

    \(\frac{5}{42}\)- X =\(\frac{11}{13}\)+\(\frac{15}{28}\)-\(\frac{11}{13}\)

   \(\frac{5}{42}\)- X =\(\frac{15}{28}\)

                X = \(\frac{5}{42}\)-\(\frac{15}{28}\)

                X = \(\frac{-5}{12}\)

b) X + \(\frac{1}{3}\)= \(\frac{2}{5}\)- ( \(\frac{-1}{3}\))

    X +\(\frac{1}{3}\) = \(\frac{11}{15}\)

   X               = \(\frac{11}{15}\)-\(\frac{1}{3}\)

   X               = \(\frac{2}{5}\)

c) \(\frac{2}{3}\)X +\(\frac{5}{7}\)=\(\frac{3}{10}\)

    \(\frac{2}{3}\)X            = \(\frac{3}{10}\)-\(\frac{5}{7}\)

    \(\frac{2}{3}\)X            =\(\frac{-29}{70}\)

             X            = \(\frac{-29}{70}\): \(\frac{2}{3}\)

            X             = \(\frac{-87}{140}\)

d) \(\frac{3}{7}\)- X =\(\frac{1}{4}\)- (\(\frac{-3}{-5}\))

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

               X  = \(\frac{109}{140}\)

e) \(\frac{-21}{-13}\)X +\(\frac{1}{3}\)=\(\frac{-2}{-3}\)

   \(\frac{-21}{-13}\)X              = \(\frac{-2}{-3}\)-\(\frac{1}{3}\)

    \(\frac{-21}{-13}\)X            =\(\frac{1}{3}\)

                   X             = \(\frac{1}{3}\):\(\frac{-21}{-13}\)

                   X             = \(\frac{13}{63}\)

Hk tốt

_Thần đồng ngu học (Toàn bài dễ)

a) x/7 = 6/21

x/7 = 2/7

=>x=2

b)2/3x -1/2=1/10

2/3x = 1/10+1/2

2/3x = 3/5

x=3/5:2/3

x=9/10

c)1/4+1/3 : x = -5

d)3x+17=2

đ)2/3x +1/4 =7/12

2x+3/10= 11/6 . 6/11

x : 4 1/3 = -2,5

a) x/7 = 6/21

x/7 = 2/7

=>x=2

b)2/3x -1/2=1/10

2/3x = 1/10+1/2

2/3x = 3/5

x=3/5:2/3

x=9/10

c)1/4+1/3 : x = -5

d)3x+17=2

đ)2/3x +1/4 =7/12

2x+3/10= 11/6 . 6/11

x : 4 1/3 = -2,5

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

\(\left(x-\frac{3}{5}\right)=-\frac{2}{165}\)

\(x=-\frac{2}{165}+\frac{3}{5}\)

\(x=\frac{97}{165}\)

vậy \(x=\frac{97}{165}\)

\(x×\left(\frac{3}{7}+\frac{2}{3}\right)=\frac{10}{21}\)

\(x×\frac{23}{21}=\frac{10}{21}\)

\(x=\frac{10}{21}:\frac{23}{21}\)

\(x=\frac{10}{23}\)

vậy \(x=\frac{10}{23}\)

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

=> \(x-\frac{3}{5}=\frac{2}{5}\cdot\left(-\frac{1}{3}\right)=-\frac{2}{15}\)

=> \(x=-\frac{2}{15}+\frac{3}{5}=-\frac{2}{15}+\frac{9}{15}=\frac{7}{15}\)

\(\frac{3}{7}x-\frac{2}{3}x=\frac{10}{21}\)

=> \(\left(\frac{3}{7}-\frac{2}{3}\right)x=\frac{10}{21}\)

=> \(-\frac{5}{21}x=\frac{10}{21}\)

=> \(x=\frac{10}{21}:\frac{-5}{21}=\frac{10}{21}\cdot\frac{-21}{5}=-2\)

Hai bài của ☆luffy cute☆ đều sai hết , xem xét lại đi nhé

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

\(\Rightarrow x-\frac{3}{5}=\frac{2}{5}\cdot\left(-\frac{1}{3}\right)=-\frac{2}{15}\)

\(\Rightarrow x=-\frac{2}{15}+\frac{3}{5}=-\frac{2}{15}+\frac{9}{15}\)

\(\Rightarrow x=\frac{7}{15}\)

2 ) \(\frac{3}{7}x-\frac{2}{3}x=\frac{10}{21}\)

\(\Rightarrow\left(\frac{3}{7}-\frac{2}{3}\right)x=\frac{10}{21}\)

\(\Rightarrow-\frac{5}{21}x=\frac{10}{21}\)

\(\Rightarrow x=\frac{10}{21}\div-\frac{5}{21}\)

\(\Rightarrow x=-2\)

* lak mũ nha

Đây là bài tìm x mà bạn

bài 1:

1/ (1-2x)²+8=17

    (1-2x)²=17-8

    (1-2x)²=9

    (1-2x)²=3²

\(\Rightarrow\orbr{\begin{cases}1-2x=3\Rightarrow2x=-2\Rightarrow x=-1\\1-2x=-3\Rightarrow2x=4\Rightarrow x=2\end{cases}}\)

Vậy x=-1 hoặc x=2

2/ (x+3)³:3-1=-10

    (x+3)³:3=-10+1

    (x+3)³:3=-9

    (x+3)³=-9.3

    (x+3)³=-27

    (x+3)³=(-3)³

     x+3   =-3

         x   =-3-3

         x   =-6

Vậy x=-6 

3/ (3x-1)³-2=-66

    (3x-1)³=-66+2

    (3x-1)³=-64

    (3x-1)³=(-4)³

     3x-1   =-4

     3x      =-4+1

     3x      =-3

       x      =-3:3

       x      =-1

Vậy x=-1

a) \(\dfrac{-15}{4}:\dfrac{21}{-10}=\dfrac{-15}{4}.\dfrac{-10}{21}=\dfrac{25}{14}\)

b) \(\dfrac{-7}{14}:\left(-0,14\right)=\dfrac{-7}{14}.\dfrac{-50}{7}=\dfrac{25}{7}\)

c) \(\left(\dfrac{-11}{15}\right):1\dfrac{1}{10}=\dfrac{-11}{15}.\dfrac{10}{11}=\dfrac{-2}{3}\)

d) \(2\dfrac{1}{7}:1\dfrac{1}{14}=\dfrac{15}{7}.\dfrac{14}{15}=2\)

\(a.-\dfrac{15}{4}:\left(\dfrac{21}{-10}\right)\)

\(=-\dfrac{15}{4}\cdot\left(-\dfrac{10}{21}\right)\)

\(=\dfrac{25}{14}\)

\(b.-\dfrac{7}{14}:\left(-0,14\right)\)

\(=-\dfrac{1}{2}:\left(-\dfrac{7}{50}\right)\)

\(=\dfrac{25}{7}\)

\(c.\left(-\dfrac{11}{15}\right):\left(1\dfrac{1}{10}\right)\)

\(=\left(-\dfrac{11}{15}\right):\dfrac{11}{10}\)

\(=-\dfrac{2}{3}\)

\(d.\left(2\dfrac{1}{7}\right):\left(1\dfrac{1}{14}\right)\)

\(=\dfrac{15}{7}:\dfrac{15}{14}\)

\(=2\)

a) \(\dfrac{-15}{4}:\dfrac{21}{-10}=\dfrac{-15}{4}.\dfrac{-10}{21}=\dfrac{25}{14}\)

b) \(\dfrac{-7}{14}:\left(-0,14\right)=\dfrac{-7}{14}:\dfrac{-7}{50}=\dfrac{-7}{14}.\dfrac{50}{-7}=\dfrac{25}{7}\)

c) \(\dfrac{-11}{15}:1.\dfrac{1}{10}=\dfrac{-11}{15}.\dfrac{1}{10}=\dfrac{-11}{150}\)

d) \(\dfrac{21}{7}:1.\dfrac{1}{14}=3.\dfrac{1}{14}=\dfrac{3}{14}\)

a) 4(x+2) - 7(2x - 1) + 9(3x - 4)=30

⇔4x+8 - 14x + 7 + 27x - 36 = 30

⇔ 17x = 51

⇔ x = 3

b) 2(5x - 8) - 3(4x - 5) = 4(3x - 4) + 11

⇔ 10x - 16 - 12x + 15 = 12x - 16 + 11

⇔ -14x = -4

⇔ x= \(\frac{2}{7}\)

c) 5x(1 - 2x) - 3x(x + 18) = 0

⇔ 5x - 10x\(^2\) - 3x\(^2\) -54x =0

⇔ -13x\(^2\) -49 x = 0

⇔ -x ( 13x + 49 ) =0

\(\Leftrightarrow\left[{}\begin{matrix}x=0\\13x+49=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\x=\frac{-49}{13}\end{matrix}\right.\)

d) 5x - 3{4x - 2[4x - 3(5x - 2)]} = 182

⇔ 5x - 3[ 4x - 2( 4x - 15x + 6 ) ]= 182

⇔5x - 3 ( 4x - 8x + 30x - 12 ) = 182

⇔ 5x - 3 ( 26x - 12 ) = 182

⇔ 5x - 78x + 36 = 182

⇔ - 73x = 146

⇔ x = -2

a) |2x-3|+x=21

|2x-3|=21-x

\(\Rightarrow\)\(\orbr{\begin{cases}2x-3=21-x\\2x-3=-\left(21-x\right)\end{cases}}\)

TH1: 2x-3=21-x

2x-x=21+3

x=24

TH2: 2x-3=-(21-x)

2x-3 = -21+x

2x-x=-21+3

x=-18

Vậy x \(\varepsilon\){-18;24}