a) \(\dfrac{6}{13}:\left(\dfrac{1}{2}-x\right)=\dfrac{15}{39}\)

\(\dfrac{1}{2}-x=\dfrac{6}{13}:\dfrac{15}{39}\)

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

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

\(x=-\dfrac{7}{10}\)

b) \(3\times\left(\dfrac{x}{4}+\dfrac{x}{28}+\dfrac{x}{70}+\dfrac{x}{130}\right)=\dfrac{60}{13}\)

\(3\times x\times\left(\dfrac{1}{4}+\dfrac{1}{28}+\dfrac{1}{70}+\dfrac{1}{130}\right)=\dfrac{60}{13}\)

\(x\times\left(\dfrac{3}{1\times4}+\dfrac{3}{4\times7}+\dfrac{3}{7\times10}+\dfrac{3}{7\times13}\right)=\dfrac{60}{13}\)

\(x\times\left(1-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{7}+\dfrac{1}{7}-\dfrac{1}{10}+\dfrac{1}{10}-\dfrac{1}{13}\right)=\dfrac{60}{13}\)

\(x\times\left(1-\dfrac{1}{13}\right)=\dfrac{60}{13}\)

\(x\times\dfrac{12}{13}=\dfrac{60}{13}\)

\(x=\dfrac{60}{13}:\dfrac{12}{13}\)

\(x=5\)

a, 720:[118-(2x -10) ]=60

           [118-(2x-10)]=720:60

           118-(2x-10)=12

                   2x-10=118-12

                    2x-10=106

                     2x     =106+10

                        2x  =116

                         x=116:2

                          x=58

câu a ko rõ ràng

Ta có \(x+5⋮x+2\)

=> x + 2 + 3 \(⋮\)x + 2

Vì x + 2  \(⋮\)x + 2

=> 3  \(⋮\)x + 2

=> x + 2 \(\in\)Ư(3)

=> x + 2  \(\in\) {1 ; 3 - 1 ; - 3}

=> x  \(\in\){-1 ; 1 ; - 3 ; - 5}

b) (x - 2)(x + 3) = 0

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

=> x  \(\in\){2 ; - 3}

c) (2x + 60)(9 - x²) = 0

=> \(\orbr{\begin{cases}2x+60=0\\9-x^2=0\end{cases}}\Rightarrow\orbr{\begin{cases}x=-30\\x=\pm3\end{cases}}\)

=> x  \(\in\){- 30 ; 3 ; - 3}

d) Vì \(x;y\inℤ\Rightarrow\hept{\begin{cases}x-2\inℤ\\y+1\inℤ\end{cases}}\)

Ta có 3 = 1.3 = (-1).(-3)

Lập bảng xét các trường hợp 

Vậy các cặp số (x ; y) thỏa mãn là (3 ; 2) ; (1 ; - 4) ; (5 ; 0) ; (- 1; - 2)

a, \(x+5⋮x+2\)

\(\Leftrightarrow x+2+3⋮x +2\)

\(\Leftrightarrow3⋮x+2\) => \(x+2\inƯ\left(3\right)=\left\{\pm1;\pm3\right\}\)

b, \(\left(x-2\right)\left(x+3\right)=0\Leftrightarrow\orbr{\begin{cases}x=2\\x=-3\end{cases}}\)

c, \(\left(2x+60\right)\left(9-x^2\right)=0\)

\(\Leftrightarrow\orbr{\begin{cases}2x+60=0\\9-x^2=0\end{cases}\Leftrightarrow\orbr{\begin{cases}2x=-60\\x^2=9\end{cases}\Leftrightarrow}\orbr{\begin{cases}x=-30\\x=\pm3\end{cases}}}\)

d, \(\left(x-2\right)\left(y+1\right)=3\Rightarrow x-2;y+1\inƯ\left(3\right)=\left\{\pm1;\pm3\right\}\)

a) \(\left(x-3\right)\left(x^2+3x+9\right)+x\left(x+2\right)\left(2-x\right)=1\)

\(\Leftrightarrow x^3-27+x\left(4-x^2\right)=1\)

\(\Leftrightarrow x^3-27+4x-x^3=1\)

\(\Leftrightarrow4x-27=1\Leftrightarrow4x=28\Leftrightarrow x=7\)

b) \(\left(x-2\right)^3-\left(x-2\right)\left(x^2+2x+4\right)+6\left(x-2\right)\left(x+2\right)=60\)

\(\Leftrightarrow x^3-6x^2+12x+4-x^3-8+6\left(x^2-4\right)=60\)

\(\Leftrightarrow-6x^2+12x-4+6x^2-24=60\)

\(\Leftrightarrow12x-28=60\Leftrightarrow x=\frac{22}{3}\)

a) (x - 3)(x^2 + 3x + 9) + x(x + 2)(2 - x) = 1

x^3 + 3x^2 + 9x - 3x^2 - 9x - 27 + 2x^2 - x^3 + 4x - 2x^2 = 1

4x - 27 = 1

4x = 28

x = 7

b) (x - 2)^3 - (x - 2)(x^2 + 2x + 4) + 6(x - 2)(x + 2) = 60

x^3 - 4x^2 + 4x - 2x^2 + 8x - 8 - x(x^2 + 2x + 4) + 2(x^2 + 2x + 4) + 6x - 24 = 60

x^3 + 12x - 32 - x^2 - 2x^2 - 4x + 2x^2 + 4x + 8 = 60

12x - 24 = 60

12x = 60 + 24

12x = 84

x = 7

giúp mình bài này với mình gấp lắm

Bài 1:

Ta có: \(4-2\left(x+1\right)=2\)

\(\Leftrightarrow2\left(x+1\right)=2\)

\(\Leftrightarrow x+1=1\)

hay x=0

Bài 2: 

Ta có: \(\left|2x-3\right|-1=2\)

\(\Leftrightarrow\left|2x-3\right|=3\)

\(\Leftrightarrow\left[{}\begin{matrix}2x-3=3\\2x-3=-3\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}2x=6\\2x=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=3\\x=0\end{matrix}\right.\)

chưa biết

ứaedrfgthyjk

a) 2840 + [(999 - 9x) : 60 ] .24 = 3200

=> [(999-9x) : 60 ] . 24 = 2840 - 3200 = -360

=>  (999 - 9x) = \(\frac{-360}{24}=-15\)

=>  9x = 999 - ( - 15) = 999 + 15 = 1014

=>  x = \(\frac{1014}{9}=\frac{338}{3}\)

b) (3x - 48) . 6 = 3³.2² - 2³.3²

(3x - 48) . 6 = 27 . 4  -  8 . 9

(3x -48).6 = 36

(3x - 48 = 36 : 6 = 6

3x = 54

x = 54 : 3 =18

 t ick cho mik nha

1)

a)    2840 + [(999-9x) :60] . 24=3200

                 [(999-9x): 60] . 24=3200- 2840= 360

                (999-9x) : 60=    360 : 24

                (999-9x) : 60= 15

                999-9x        =15 . 60

                  999-9x       =900

                         9x=    999-900=9

                          x=9:9=1

b)   (3x - 48).6=    3³.2²-2³.3²

      (3x-48).6  =   27.4-8.9

       (3x - 48)6  =  108-72

        (3x - 48)6  = 36

       (3x-48)    =   36:6=6

        3x        = 6 + 48

        3x=54

          x=54:3=18