e: =>2/7-x=2/5

=>7-x=5

=>x=2

f: =>2x+3/3=10/3

=>2x+3=10

=>2x=7

=>x=7/2

g: =>(14+x)/7=15/7

=>x+14=15

=>x=1

h: =>(2x+3)/x=13/x

=>2x+3=13

=>2x=10

=>x=5

^{a, -15×(x+2)+7×(2x-3)=-50}

-15×x+-30+14×x-21=-50

-15×x+14×x=-50+30+21

-x=1

X=-1

a) -15.(x+2)+7.(2x-3)= (-50)

=>-15x-30+14x-21=-50

=>(-15x+14x)-30-21=-50

=>-x-51=-50

=>-x=1

=>x=-1

b)2(x+1)²=-7+15

=>2(x+1)²=8

=>(x+1)²=4

=>x+1=2 hoặc -2

=>x=1 hoặc -3

a) 125 : x + ( 32 + 15 ) = 72

    125 : x + 47             = 72

    125 : x                     = 72 - 47

    125 : x                     = 25

            x                      = 125 : 25

           x                       = 5

b) ( 35 + 135 ) - 2 . x = 86

          170 - 2 . x       = 86

                   2 . x       = 170 - 86

                   2 . x       = 84

                        x      = 84 : 2

                       x      = 42

c) 7 . x - 5 = 65

    7 . x      = 65 + 5

    7 . x      = 70

        x       = 70 : 7

        x       = 10

A) 125 / x + (32 + 15) = 72

   125 / x + 47             = 72

    125 / x                     = 72 - 47

    125 / x                     = 25

     x                             = 125 / 25

     x                             =  5   

B)

(35 + 135) - 2 x x = 86

170 - 2 x x             = 86 

2 x x                      = 170-86

2 x x                      = 84

x                            = 84/2

x                            = 42

Mình trả lời hai câu đầu trước nha!

1)

x= -6+2

x= -4

2)

=-5 x = 13 + (-3)

= -5 .x =10

x = 10 ÷ -5

x = -2

x - 7 = 15 - (-21)

x - 7 = 36

x = 36 + 7

x = 43

b) 3x + 17 = 2

3x = 2 - 17

3x = -15

x = -5

c) ( x - 9) = 45 - ( -35)

x - 9 = 80

x = 80 + 9

x = 89  

a/ \(15-\left(x-7\right)=-21\)

\(15-x+7=-21\)

\(x=15-\left[\left(-21\right)-7\right]=15-\left(-28\right)=43\)

b/\(3x+17=2\)

\(3x=2-17=-15\)

\(x=-\frac{15}{3}=-5\)

c/\(45-\left(x-9\right)=-35\)

\(45-x+9=-35\)

\(x=45-\left[\left(-35\right)-9\right]=89\)

d/\(\left(-5\right)+x=15\)

\(x=15-\left(-5\right)=20\)

e/\(2x-\left(-17\right)=15\)

\(2x=15-17=-2\)

\(x=-\frac{2}{2}=-1\)

g/ \(Ix-2I=3\)

TH1: \(x-2=3\)

\(x=3+2=5\)

TH2: \(x-2=-3\)

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

=> \(x\in\left\{-1;5\right\}\)

giải:

a) 15 - ( x - 7 ) = -21

            x - 7   = 15 - ( -21 ) = 36

            x        = 36 + 7

            x        = 43

b) 3x + 17 = 2

    3x        = 2 - 17 = -15

      x        = -15 : 3

      x        = -5

c) 45 - ( x - 9 ) = -35

             x - 9 = 45 - ( -35 ) = 80

             x      = 80 + 9

             x      = 89

d) ( -5 ) + x = 15

               x = 15 - (-5 )

               x = 20

e) 2x - ( -17 ) = 15

    2x             = 15 + ( -17 ) = -2

     x              = -2 : 2

     x              = -1

g) | x - 2 | = 3

ta có 2 trường hợp

TH1 : x - 2 = 3

         x      = 3 + 2

         x      = 5

TH2: x - 2 = -3

        x     = -3 + 2

        x     = -1

vậy x = { -1;5}

a) \(6x+15\times8=12\times\left(19-x\right)\)

\(6x+120=228-12x\)

\(6x+120-228+12x=0\)

\(18x-108=0\)

\(18x=108\)

\(x=6\)

b) \(160-\left(35\div x+3\right)\times15=15\)

\(160-\left(35\div x+3\right)=1\)

\(35\div x+3=159\)

\(35\div x=156\)

\(x=\dfrac{35}{156}\)

c) \(2x-\left(1309\div11-19\right)-2=0\)

\(2x-1309\div11-19=2\)

\(2x-119-19=2\)

\(2x-119=21\)

\(2x=140\)

\(x=70\)

d) \(\left(x-7\right)\times\left(2x-16\right)=0\)

\(x-7=0;2x-16=0\)

\(x=7;2x=16\)

\(x=7;x=8\)

a) $6x+15\times 8=12\times \left(19-x\right)$

$6x+120=228-12x$

$6x+120-228+12x=0$

$18x-108=0$

$18x=108$

$x=6$

b) $160-\left(35÷x+3\right)\times 15=15$

$160-\left(35÷x+3\right)=1$

$35÷x+3=159$

$35÷x=156$

�=35156x=15635​
 

a) 42 - x = 5

x = 42 - 5

x = 37

b) 15.(x + 4) = 75

x + 4 = 75 : 15

x + 4 = 5

x = 5 - 4

x = 1

d) x + 18 = 12

x = 12 - 18

x = -6

e) 2x - 15 = -19

2x = (-19) + 15

2x = -4

x = -4 : 2

x = -2

f) 36 : (x^3 - 12) = -3

x^3 - 12 = 36 : (-3)

x^3 - 12 = -12

x^3 = 0

=> x = 0

g)x + 15 = 35

x = 35 - 15

x = 20

h) 2x - 13 = 3^2

2x - 13 = 9

2x = 9 + 13

2x = 22

x = 22 : 2

x = 11

a) 42-x=5

         x=42-5

         x= 37

b)15*(x+4)=75

        x+4=75:15

        x+4=5

        x    =5-4

       x     = 1

a) 42 - x = 5

x = 42 - 5

x = 37

b) 15.(x + 4) = 75

x + 4 = 75 : 15

x + 4 = 5

x = 5 - 4

x = 1

d) x + 18 = 12

x = 12 - 18

x = -6

e) 2x - 15 = -19

2x = (-19) + 15

2x = -4

x = -4 : 2

x = -2

f) 36 : (x^3 - 12) = -3

x^3 - 12 = 36 : (-3)

x^3 - 12 = -12

x^3 = 0

=> x = 0

g)x + 15 = 35

x = 35 - 15

x = 20

h) 2x - 13 = 3^2

2x - 13 = 9

2x = 9 + 13

2x = 22

x = 22 : 2

x = 11

a.

\(15-\left(x-7\right)=-21\)

\(x-7=15-\left(-21\right)\)

\(x-7=36\)

\(x=36+7\)

\(x=43\)

b.

\(3x+17=2\)

\(3x=2-17\)

\(3x=-15\)

\(x=-15\div3\)

\(x=-5\)

c.

\(45-\left(x-9\right)=-35\)

\(x-9=45-\left(-35\right)\)

\(x-9=80\)

\(x=80+9\)

\(x=89\)

d.

\(\left(-5\right)+x=15\)

\(x=15-\left(-5\right)\)

\(x=20\)

e.

\(2x-\left(-17\right)=15\)

\(2x=15+\left(-17\right)\)

\(2x=-2\)

\(x=-2\div2\)

\(x=-1\)

g.

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

\(x-2=\pm3\)

               \(x=3-2\)

               \(x=1\)

                \(x=-3+2\)

                \(x=-1\)

Vậy x = 1 hoặc x = - 1.

Chúc bạn học tốt

a)

15-(x-7)=-21

x-7=15-(-21)

x-7=36

x=36+7

x=43

b)

3x+17=2

3x=17-2

3x=15

x=15:3

x=5

c)

45-(x-9)=-35

x-9=45-(-35)

x-9=80

x=80+9

x=89

d)

(-5)+x=15

x=15-(-5)

x=20

e)

2x-(-17)=15

2x=15+(-17)

2x=-2

x=-2:2

x=-1

g)

TH1

|x-2|=3

x-2=3

x=3+2

x=5

TH2

|x-2|=3

x-2=-3

x=-3+2

x=-1

-15x - 30 + 14x - 21 -50 = 0

-15x + 14x = 50 + 21 + 30

-x = 101

x = -101

=> -15x+(-30)+14x-21=50

=>(15x-14x)-(30+21)=50

x-51=50

x=-101