a: =>x/-3=3

hay x=-9

b: =>x/9=-1/9

hay x=-1

c: =>x+1/5=-1/3

hay x=-8/15

d: =>-7/x=-7/9

hay x=9

a, \(\dfrac{x}{-3}=3\Leftrightarrow x=-9\)

b, \(\dfrac{x}{9}=-\dfrac{1}{9}\Rightarrow x=-1\)

c, \(\dfrac{x+3}{15}=-\dfrac{6}{15}\Rightarrow x=-9\)

d, \(\dfrac{42}{-54}=-\dfrac{42}{6x}\Rightarrow6x=54\Leftrightarrow x=9\)

`#3107.101107`

`(3x - 15) . 17 = 42`

`\Rightarrow 3x - 15 =` $\dfrac{42}{17}$

`\Rightarrow 3x =` $\dfrac{42}{17} + 15$

`\Rightarrow 3x =` $\dfrac{297}{17}$

`\Rightarrow x =` $\dfrac{297}{17} \div 3$

$\Rightarrow x = \dfrac{99}{17}$

Vậy, $x = \dfrac{99}{17}.$

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: x=27

a: x=27

x-42=-15+27:9

x-42=-15+3

x-42=-12

x=-12+42

x=30

Vậy x=30

x-42= -15+27÷3^2

x-42= -15+27÷9

x-42= -15+3

x-42= -12

x= -12+42

x= 42-12

x= 30

Chúc bạn học tốt!

X - 42 = - 15 + 27 : 3²

X - 42 = - 15 + 27 : 9

X - 42 = - 15 + 3

X - 42 = - 12

X = ( - 12 ) + 42

X = 30

X -42=-15+27:3²

=> x -42= -15 +27 :9

=> x-42 = -15 +3

=> x-42= -12

=>x= 42+-12

=> x=30

<=> 126 - 3x + 15 = 8 x 3 x 5

<=> 3x = 126 + 15 - 8 x 3 x 5

<=> 3x = 21

<=> x = 7

[3 (42-X )+15]÷5=2^3×3

[3 (42-x )+15]÷5=8×3

[3 (42-x )+15]÷5=24

3 (42-x )+15=24×5

3 (42-x )+15=120

3 (42-x )=120-15

3 (42-x )=105

42-x=105÷3

42-x=35

x=42-35

x=7

16 giờ 9 phút

a, \(x\) + 99: 3 = 55

    \(x\) + 33 = 55

     \(x\)        = 55 - 33

      \(x\)       = 22

b, (\(x\) - 25):15 = 20

       \(x\) - 25  = 20 x 15

       \(x\) - 25  = 300

        \(x\)         = 300 + 25

          \(x\)        = 325

c, (3\(x\) - 15).7 = 42

      3\(x\) - 15 = 42:7

       3\(x\) - 15 = 6

        3\(x\)         = 6 + 15

         3\(x\)         = 21

            \(x\)         = 21: 3

             \(x\)         = 7

d, (8\(x\) - 16).(\(x\) -5) = 0

       \(\left[{}\begin{matrix}8x-16=0\\x-5=0\end{matrix}\right.\)

         \(\left[{}\begin{matrix}8x=16\\x=5\end{matrix}\right.\)

          \(\left[{}\begin{matrix}x=16:8\\x=5\end{matrix}\right.\)

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

Vậy \(x\) \(\in\) {2; 5}

x - 18 - 42 = 23 - 43 - 70 - x

\(\rightarrow\) 2x = -30

\(\rightarrow\) x = -15

\(\left(-\left(x+15\right)\right)^2\) - 19 = \(3^2\) .5

\(\rightarrow\)\(x^2+30x+225\) - 19 = 45

\(\rightarrow x^2+30x+161=0\)

\(\rightarrow x^2+23x+7x+161=0\)

\(\rightarrow x\left(x+23\right)+7\left(x+23\right)=0\)

\(\rightarrow\left(x+7\right)\left(x+23\right)=0\)

\(\rightarrow\) x = -7 hoặc x = -23