a, \(\dfrac{3}{7}\)\(x\) - 0,4 = - \(\dfrac{17}{35}\)

    \(\dfrac{3}{7}\)\(x\)         = - \(\dfrac{17}{35}\) + 0,4

     \(\dfrac{3}{7}\)\(x\)       = - \(\dfrac{3}{35}\)

        \(x\)       = - \(\dfrac{3}{35}\): \(\dfrac{3}{7}\)

        \(x\)       = - \(\dfrac{1}{5}\)

b, 0,2.(\(x\) - 3) +2,4 = 10

    0,2.(\(x\) - 3)          = 10 - 2,4

    0,2.(\(x\) - 3)          = 7,6

           \(x\) - 3            = 7,6:0,2

           \(x\) - 3            = 38

            \(x\)                = 38 + 3

             \(x\)                = 41

\(\dfrac{3}{7}x-0,4=\dfrac{-17}{35}\)

\(\dfrac{3}{7}x=\dfrac{-17}{35}+0,4=\dfrac{-34}{70}+\dfrac{28}{70}\)

\(\dfrac{3}{7}x=\dfrac{-6}{70}=\dfrac{-3}{35}\)

\(x=\dfrac{-3}{35}:\dfrac{3}{7}=\dfrac{-3}{35}\cdot\dfrac{7}{3}\)

\(x=\dfrac{3\cdot\left(-1\right)\cdot7}{5\cdot7\cdot3}=-\dfrac{1}{5}\)

b) \(0,2\left(x-3\right)+2,4=10\)

\(0,2\left(x-3\right)=10-2,4=7,6\)

\(x-3=7,6:0,2=38\)

\(x=38+3=41\)

c) \(\left(x:2,2\right)\cdot\dfrac{1}{6}=\dfrac{-3}{8}\cdot\left(0,5-1\dfrac{3}{5}\right)\)

\(\left(x:2,2\right)\cdot\dfrac{1}{6}=\dfrac{-3}{8}\cdot\dfrac{-11}{10}\)

\(x:2,2=\dfrac{-3}{8}\cdot\dfrac{-11}{10}\cdot\dfrac{6}{1}\)

\(x:2,2=\dfrac{-3\cdot\left(-11\right)\cdot2\cdot3}{2\cdot4\cdot10\cdot1}=\dfrac{99}{40}\)

\(x=\dfrac{99}{40}\cdot2,2=\dfrac{99}{40}\cdot\dfrac{22}{10}\)

\(x=\dfrac{99\cdot2\cdot11}{40\cdot2\cdot5}=\dfrac{1089}{200}\)

\(a,5,2x+7\dfrac{2}{5}=6\dfrac{3}{4}\\ \Rightarrow\dfrac{26}{5}x+\dfrac{37}{5}=\dfrac{27}{4}\\ \Rightarrow\dfrac{26}{5}x=-\dfrac{13}{20}\\ \Rightarrow x=-\dfrac{1}{8}\\ b,2,4:\left(\dfrac{-1}{2}-x\right)=1\dfrac{3}{5}\\ \Rightarrow\dfrac{12}{5}:\left(\dfrac{-1}{2}-x\right)=\dfrac{8}{5}\\ \Rightarrow\dfrac{-1}{2}-x=\dfrac{3}{2}\\ \Rightarrow x=-2\)

2,4 . x =6/5 . 0,4

2,4 . x=12/25

x=12/25:2,4

x=1/5

`2,4 xx x=6/5xx0,4`

`2,4x=6/5xx2/5`

`12/5x=12/25`

`x=12/25:12/5`

`x=1/5`

2,4 * x = \(\dfrac{6}{5}\) * 0,4

   2,4 * x = \(\dfrac{12}{25}\)

      x = \(\dfrac{12}{25}\) : 2,4

        x = \(\dfrac{1}{5}\)

                                                       From#GDucky

a) Ta được: x . 1,25 = 5. (-2) nên \(x = \frac{{5.( - 2)}}{{1,25}} =  - 8\)

Vậy x = -8

b) Vì 18 : x = 2,4 : 3,6 nên \(\frac{{18}}{x} = \frac{{2,4}}{{3,6}} \Rightarrow 18.3,6 = x.2,4 \Leftrightarrow x = \frac{{18.3,6}}{{2,4}} = 27\)

Vậy x = 27

c) Vì (x+1) : 0,4 = 0,5 : 0,2 nên \(\frac{{x + 1}}{{0,4}} = \frac{{0,5}}{{0,2}} \Rightarrow (x + 1).0,2 = 0,4.0,5 \Leftrightarrow x + 1 = \frac{{0,4.0,5}}{{0,2}} = 1 \Leftrightarrow x = 0\)

Vậy x = 0

a, x= (-2). 5 :1,25 = -8

b, x= 18 : (2,4:3,6)= 18: 2/3 = 18 x 3/2 = 27

c, x+1= (0,5:0,2) x 0,4= 2,5 x 0,4= 1

=> x=1-1=0

`1/x + y/3 = 5/6`

`-> 1/x = 5/6 - y/3`

`-> 1/x = 5/6 - ( 2y ) / 6`

`-> 1/x = ( 5 - 2y ) / 6`

`-> x ( 5 - 2y ) = 6`

\(x,y\in Z\)

\(\dfrac{1}{x}+\dfrac{y}{3}=\dfrac{5}{6}\left(x\ne0\right)\)

\(\Rightarrow\dfrac{6}{6x}+\dfrac{2xy}{6x}=\dfrac{5x}{6x}\)

\(\Rightarrow6+2xy=5x\)

\(\Rightarrow5x-2xy=6\)

\(\Rightarrow x\left(5-2y\right)=6\)

\(\Rightarrow x=\dfrac{6}{5-2y}\left(y\ne\dfrac{5}{2}\right)\)

Vì x,y là các số nguyên nên:

\(6⋮\left(5-2y\right)\)

\(\Rightarrow5-2y\inƯ\left(6\right)\)

\(\Rightarrow5-2y\in\left\{1;2;3;6;-1;-2;-3;-6\right\}\)

\(\Rightarrow y\in\left\{2;1;3;4\right\}\)

*\(y=2\text{​​}\Rightarrow x=\dfrac{6}{5-2.2}=6\left(n\right)\)

\(y=1\text{​​}\Rightarrow x=\dfrac{6}{5-2.1}=2\left(n\right)\)

\(y=3\text{​​}\Rightarrow x=\dfrac{6}{5-2.3}=-6\left(n\right)\)

\(y=4\text{​​}\Rightarrow x=\dfrac{6}{5-2.4}=-2\left(n\right)\)

Vậy các cặp số x,y nguyên thỏa mãn (phương trình) là (6,2) ; (2,1) ; (-6,3) ; (-2,4).

Giúp mk đi.

\(a,28,7\times2,4+2,4\times34,5\\ =\left(28,7+34,5\right)\times2,4\\ =151,68\\ b,9,65\times0,4\times2,5\\ =9,65\times1\\ =9,65\)

  A,

`28,7 xx 2,4 + 2,4 xx 34,5 `

`= 2,4 xx ( 28,7 + 34,5 ) `

`= 2,4 xx 63,2 `

`= 2151,68`

B

` 9,65 xx 0,4 xx 2,5`

`= 9,65 xx (0,4 xx 2,5)`

`= 9,65 xx 1`

`=9,65`

9.65

a)2,3:x+3,4:x=6

=>5,7/x=6

=>x=0,95

b)10,2:x+4,5:x=14

=>14,7:x=14

=>x=1,05

c)Xx4,9+x:10

=>49xX:10+x:10=102:10

=>50xX=102

=>x=2,04

d)4,1x-x:10=2,4

=>41x:10-x:10=24:10

=>40x=24

=>x=0,6

còn lại bạn tự làm nha mỏi tay quá

nhớ
 

a: Sửa đề: \(A=\dfrac{\sqrt{x}+1}{\sqrt{x}-3}\)

ĐKXĐ: \(\left\{{}\begin{matrix}x>=0\\x\ne9\end{matrix}\right.\)

Để A là số nguyên thì \(\sqrt{x}+1⋮\sqrt{x}-3\)

=>\(\sqrt{x}-3+4⋮\sqrt{x}-3\)

=>\(4⋮\sqrt{x}-3\)

=>\(\sqrt{x}-3\in\left\{1;-1;2;-2;4;-4\right\}\)

=>\(\sqrt{x}\in\left\{4;2;5;1;7;-1\right\}\)

=>\(\sqrt{x}\in\left\{4;2;5;1;7\right\}\)

=>\(x\in\left\{16;4;25;1;49\right\}\)

b: