=>3x(1-1/6)=3/4

=>3x=3/4:5/6=3/4*6/5=18/20=9/10

=>x=3/10

Đề là \(3x\left(\dfrac{1}{1}\times\dfrac{1}{2}+\dfrac{1}{2}\times\dfrac{1}{3}+\dfrac{1}{3}\times\dfrac{1}{4}+\dfrac{1}{4}\times\dfrac{1}{5}+\dfrac{1}{5}\times\dfrac{1}{6}\right)=\dfrac{3}{4}?\)

`3x (1/1 \times 1/2 + 1/2 \times 1/3 + 1/3 \times 1/4 + 1/4 \times 1/5 + 1/5 \times 1/6) = 3/4`

\(3x\left(\dfrac{1}{1\times2}+\dfrac{1}{2\times3}+\dfrac{1}{3\times4}+\dfrac{1}{4\times5}+\dfrac{1}{5\times6}\right)=\dfrac{3}{4}\)

\(3x\left(\dfrac{1}{1}-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{6}\right)=\dfrac{3}{4}\)

\(3x\left(1-\dfrac{1}{6}\right)=\dfrac{3}{4}\)

\(3x\times\dfrac{5}{6}=\dfrac{3}{4}\)

`3x=3/4 \div 5/6`

`3x = 9/10`

`x = 9/10 \div 3`

`x = 3/10.`

\(\dfrac{x-1}{x}-\dfrac{1}{x+1}=\dfrac{2x-1}{x^2+x}\)

\(\Leftrightarrow\dfrac{x-1}{x}-\dfrac{1}{x+1}=\dfrac{2x-1}{x\left(x+1\right)}\)

ĐKXĐ : \(\left\{{}\begin{matrix}x\ne0\\x+1\ne0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x\ne0\\x\ne-1\end{matrix}\right.\)

Ta có : `(x-1)/x -1/(x+1) =(2x-1)/(x(x+1))`

\(\Leftrightarrow\dfrac{\left(x-1\right)\left(x+1\right)}{x\left(x+1\right)}-\dfrac{x}{x\left(x+1\right)}=\dfrac{2x-1}{x\left(x+1\right)}\)

`=> x^2 +x -x-1 -x-2x+1=0`

`<=> x^2 -3x =0`

`<=> x(x-3)=0`

\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x-3=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\left(ktm\right)\\x=3\end{matrix}\right.\)

__

`(x+2)(5-3x)=0`

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

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

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

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\(\dfrac{5\left(1-2x\right)}{3}+\dfrac{x}{2}=\dfrac{3\left(x-5\right)}{4}-2\)

\(\Leftrightarrow\dfrac{20\left(1-2x\right)}{12}+\dfrac{6x}{12}=\dfrac{9\left(x-5\right)}{12}-\dfrac{24}{12}\)

`<=> 2x- 40x + 6x = 9x - 45 -24`

`<=>  2x- 40x + 6x-9x + 45 +24=0`

`<=>-41x+69=0`

`<=>-41x=-69`

`<=> x=69/41`

Cậu tách 2 câu 1 lượt mn trl nhanh hơn đó ạ

Bài dài quá, lần sau chia nhỏ câu hỏi nhé!!!!!

đúng vậy

Dài thế trời!!!

1) 1/3 x 1/2 x 3/7 = 1/6 x 3/7 = 1/14

2) 5/4 x 1/3 + 1/7 = 5/12 + 1/7 = 47/84

3) 8 x (8/9 - 2/3) = 8 x 2/9 = 16/9

4) 5/6 x 48/20 x 1/2 = 2 x 1/2 = 1

5) (2/5 + 3/4) x 8 = 23/20 x 8 = 46/5

6) 10 x (1/2 - 1/5) = 10 x 3/10 = 3

\(\dfrac{1}{5}\times x-\dfrac{2}{3}=\dfrac{1}{10}\times x+\dfrac{5}{6}\)

\(\dfrac{1}{5}x-\dfrac{2}{3}-\dfrac{1}{10}x-\dfrac{5}{6}=0\)

\(\dfrac{1}{5}x-\dfrac{1}{10}x-\dfrac{2}{3}-\dfrac{5}{6}=0\)

\(\dfrac{1}{10}x-\dfrac{3}{2}=0\)

\(\dfrac{1}{10}x=\dfrac{3}{2}\)

\(x=15\)

           \(\dfrac{1}{5}\).x - \(\dfrac{2}{3}\) = \(\dfrac{1}{10}\).x + \(\dfrac{5}{6}\)

⇒   \(\dfrac{1}{5}\).x - \(\dfrac{1}{10}\).x = \(\dfrac{5}{6}\) + \(\dfrac{2}{3}\)

⇒ \(\dfrac{2}{10}\).x - \(\dfrac{1}{10}\).x = \(\dfrac{5}{6}\) + \(\dfrac{4}{6}\)

⇒            \(\dfrac{1}{10}\).x = \(\dfrac{9}{6}\)

⇒                  x = \(\dfrac{9}{6}\) : \(\dfrac{1}{10}\)

⇒                  x = \(\dfrac{9}{6}\) . 10

⇒                  x = \(\dfrac{90}{6}\)

⇒                  x = 15

       Vậy x = 15

Giúp mình nhanh nha! Mình sẽ thick người đó

a) 3 3/4 . x = 1 1/2

<=> 15/4 . x = 3/2

<=> x = 3/4 . 4/15

<=> x = 1/5

Vậy x = 1/5

b) 1 1/4 x + 1 1/2 = 1 1/4

<=> 5/4 . x + 3/2 = 5/4

<=> 5/4 . x = 5/4 - 3/2

<=> 5/4 . x = -1/4

<=> x = -1/4 . 4/5

<=> x = -1/5

Vậy x = -1/5

c) ( 3 1/3 - 1 1/2 x ) : 5/6 = 1 1/2

<=> ( 10/3 - 3/2 x ) : 5/6 = 3/2

<=> 10/3 - 3/2 x = 3/2 . 5/6

<=> 10/3 - 3/2 x = 5/4

<=> 3/2 . x = 10/3 - 5/4

<=> 3/2 . x = 25/12

<=> x = 25/12 . 2/3

<=> x = 25/18

Vậy x = 25/18

d) ( 3/7 x - 1 ) : 4 = -1/28

<=> 3/7 . x - 1 = -1/28 . 1/4

<=> 3/7 . x - 1 = -1/112

<=> 3/7 . x = -1/112 + 1

<=> 3/7 . x = 111/112

<=> x = 111/112 . 7/3

<=> x = 37/16

Vậy x = 37/16

e) | x - 3/4 | = 1

<=> x - 3/4 = 1

hoặc x - 3/4 = -1

<=> x = 1 + 3/4

hoặc x = -1 + 3/4

<=> x = 7/4

hoặc x = -1/4

Vậy x = 7/4 ; x = -1/4

f) | 2/3 . x + 1/3 | = 5/6

<=> 2/3 . x + 1/3 = 5/6

hoặc 2/3 . x + 1/3 = -5/6

<=> 2/3 . x = 5/6 - 1/3

hoặc 2/3 . x = -5/6 - 1/3

<=> 2/3 . x = 1/2

hoặc 2/3 . x = -7/6

<=> x = 1/2 . 3/2

hoặc x = -7/6 . 3/2

<=> x = 3/4

hoặc x = -7/4

Vậy x = 3/4 ; x = -7/4