3x +8 chia hết cho x+2

3(x+2) chia hết choi x+2

=>3x+8 -3(x+2) chia hết cho x+2

=>3x+8-3x-6 chia hết chia x +2

=>2 chia hết cho x+2

=>x+2\(\in\)Ư(2)={1;-1;2;-2}

Ta có bảng sau:

Vậy x=0

Bài 1: Tìm x, biết     

a )24-(36+5)=x                              b)14-21=(13-x)-(15+8)                         

    24-41=x                                      (13-x)-23=-7 

    x=-17                                          13-x=(-7)+23

Vậy x=-17                                        13-x=16

                                                        x=13-16

                                                        x=-3                 Vậy x=-3

Bài 2:Tìm x, biết

a)17-x=-25+(-16+9)                           b)3x-21=-19-(-2x)                

   17-x=-25+(-7)                                   3x-21=-19+2x

    17-x=-32                                         3x-2x=-19+21

     x=17-(-32)                                       x=4

     x=49                                                    Vậy x=4

Vậy x=49

Bài 1:

a. 24 - (36+5) = x

=> 24 - 41 = x

=> -17 = x

=> x = -17

b. 14 - 21 = (13 - x) - (15 + 8)

=> -7 = 13 - x - 23

=> -7 - 13 + 23 = -x

=> 3 = -x

=> x = -3

Bài 2:

a. 17 - x = -25 + (-16 + 9)

=> 17 - x = -25 + (-7)

=> 17 - x = -32

=> 17 + 32 = x 

=> x = 49

b. 3x - 21 = -19 - (-2x)

=> 3x - 21 = -19 + 2x

=> 3x - 2x = -19 + 21

=> x = 2

Bài1

a)24-(36+5)=x\(\Rightarrow\)x=24-41=-17

b)14-21=(13-x)-(15+8)\(\Rightarrow\)(13-x)-(15+8)=-7\(\Rightarrow\)13-x=-7+23=16\(\Rightarrow\)x=13-16=-3

Bài2

a)17-x=-25+(-16+9)\(\Rightarrow\)17-x=-25+-7\(\Rightarrow\)17-x=-32\(\Rightarrow\)x=17-(-32)=17+32=49

b)3x-21=-19-(-2x)\(\Rightarrow\)3x-(-2x)=-19-21\(\Rightarrow\)3x+2x=-40\(\Rightarrow\)5x=-40\(\Rightarrow\)x=-8

\(25\%x-\frac{7}{8}+x=\frac{2}{3}x\)

<=> \(\frac{1}{4}x-\frac{7}{8}+1x=\frac{2}{3}x\)

<=> \(\frac{1}{4}x+1x-\frac{2}{3}x=\frac{7}{8}\)

<=> \(x\left(\frac{1}{4}+1-\frac{2}{3}\right)=\frac{7}{8}\)

<=> \(x\cdot\frac{7}{12}=\frac{7}{8}\)

<=> \(x=\frac{12}{8}=\frac{3}{2}\)

Bài làm:

Ta có: \(25\%x-\frac{7}{8}+x=\frac{2}{3}x\)

\(\Leftrightarrow\frac{x}{4}+x-\frac{2}{3}x=\frac{7}{8}\)

\(\Leftrightarrow\frac{7}{12}x=\frac{7}{8}\)

\(\Leftrightarrow x=\frac{3}{2}\)
 

B, => 2x+5=3x-8

2x-3x=-8-5

-x=-13

=>x=13

hoặc 2x+5=-3x+8

2x+3x=8-5

5x=3

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

\(\left|x+1\right|+\left|x-5\right|=7.\)

\(Th1:x+1< 0;x-5< 0\)

\(x< -1;x< 5\Rightarrow x< -1\)

\(\left|x+1\right|+\left|x-5\right|=7\)

\(-\left(x+1\right)-\left(x-5\right)=7\)

\(-x-1-x+5=7\)

\(-2x+4=7\)

\(-2x=3\)

\(x=-1,5\left(tm\right)\)

\(Th2:x+1>0;x-5>0\)

\(x>-1;x>5\Rightarrow x>5\)

\(\left|x+1\right|+\left|x-5\right|=7\)

\(x+1+x-5=7\)

\(2x-4=7\)

\(2x=11\)

\(x=5,5\)\(\left(tm\right)\)

\(Th3:x+1\le0;x-5>0\)

\(x\le-1;x>5\)(không xảy ra)

\(Th4:x+1>0;x-5\le0\)

\(x>-1;x\le5\Rightarrow-1< x\le5\)

\(\left|x+1\right|+\left|x-5\right|=7\)

\(-\left(x+1\right)+x-5=7\)

\(-x-1+x-5=7\)( không xảy ra) 

Vậy  x = -1,5 hoặc x = 5,5

\(\)

\(\left|2x+5\right|=3x-8.\)

\(Th1:\)

\(2x+5=-\left(3x-8\right)\)

\(2x+5=-3x+8\)

\(2x+3x=8-5\)

\(5x=3\)

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

\(Th2:\)

\(2x+5=3x-8\)

\(2x-3x=-8-5\)

\(-x=-13\)

\(x=13\)

Vậy x = 13 hoặc x = \(\frac{3}{5}\)

4x(3x - 5) + 2x(8 - 6x) = 24

12x² - 20x + 16x - 12x² = 24

-4x = 24

x = -6

* Chúc bạn học tốt .

4x(3x -5)+2x(8-6x) =24

=>2x(3x-5)+x(8-6x)=12

=>6x²-10x+8x-6x²=12

=>-2x=12

=>x=-6

=>x+6=0

=>x=-6