a: =>-12x=60-12=48

=>x=-4

b: =>-5x=24+6-5=25

=>x=-5

Chi tiết nha

Lời giải:
a.

$(-12).x=(-15)(-4)-12$

$(-12)x=60-12=48$

$x=48:(-12)=-4$

b.

$(-5)x+5=(-3)(-8)+6$

$(-5)x+5=24+6=30$

$(-5)x=30-5=25$

$x=25:(-5)=-5$

a) x+7=-12

        x=(-12)-7

        x=-19

b)x-15=-21

        x=(-21)+15

        x=-6

c)13-x=20

        x=13-20

        x=-7

d)17-(2+x)=3

      x=17-3

      x=14

      x=14-2

      x=12

a,x+7=-12

=>x= -12-7

=>x= -19

b,x-15= -21

=>x= -21+15

=>x= -6

c,13-x=20

=>x=13-20

=>x= -7

d, 17-(2+x)=3

=>2+x=17-3

=>2+x=14

=>x=14-2

=>x=12

a) \(x+7=-12\) 

    \(x=-12-7\) 

    \(x=-19\) 

b) \(x-15=-21\)  

    \(x=-21+15\) 

    \(x=-6\)  

c) \(13-x=20\) 

            \(x=13-20\)  

            \(x=-7\) 

d) \(17-\left(2+x\right)=3\)  

             \(2+x=17-3\)  

             \(2+x=14\)   

                   \(x=14-2\)  

                   \(x=12\)

a,(-12).x= 60-12

(-12).x=48

x=48:(-12)

x = -4

b,(-5).x + 5 = -24+6

(-5).x + 5 = 30

(-5).x      = 30-5

(-5).x      = 25

x = 25 : (-5)

x = -5

c,

$3x+36=-7x-64$

$10x=-100$

$x=-10$

$b,-5x-178=14x+145$

$-19x=323$

$x=-17$

a: \(\Leftrightarrow\dfrac{x}{-4}=\dfrac{21}{y}=\dfrac{z}{-80}=\dfrac{3}{4}\)

=>x=-3; y=28; z=-60

b: 5/12=x/-72

=>x=-72*5/12=-6*5=-30

c: =>x+3=-5

=>x=-8

1)

\(x-17=23\\ \Rightarrow x=23+17\\ \Rightarrow x=40\)

2)

\(2\left(x-1\right)=7+\left(-3\right)\\ \Rightarrow2x-2=4\\ \Rightarrow2x=4+2\\ \Rightarrow2x=8\\ \Rightarrow x=4\)

3)

\(4\left(x+5\right)^3-7=101\\ \Rightarrow4\left(x+5\right)^3=101+7\\ \Rightarrow4\left(x+5\right)^3=108\\ \Rightarrow\left(x+5\right)^3=108\div4\\ \Rightarrow\left(x+5\right)^3=27\\ \Rightarrow\left(x+5\right)^3=3^3\\ \Rightarrow x+5=3\Rightarrow x=3-5\\ \Rightarrow x=-2\)

4)

\(2^{x+1}\times3+15=39\\ \Rightarrow2^{x+1}\times3=39-15\\ \Rightarrow2^{x+1}\times3=24\\ \Rightarrow2^{x+1}=24\div3\\ \Rightarrow2^{x+1}=8\)

\( \Rightarrow2^{2+1}=8\\\Rightarrow2^3=8\Rightarrow x=2 \)

a) x - 17 = 23

x = 23 + 17

x = 40

Vậy x = 40

b) 2 ( x - 1 ) = 7 + ( - 3 )

x - 1 = 4 : 2

x = 2 + 1

x = 3

Vậy x = 3

c) 4 ( x + 3 )^3 - 7 = 101

4 ( x + 3 )^3 = ( 101 + 7 ) : 4

( x + 3 )^3 = 3^3

⇒ x + 3 = 3

⇒ x = 0

Vậy x = 0

d) 2^{ x+ 1 } . 3 + 15 = 39

2^{ x + 1 } = ( 39 - 15 ) : 3

2^{ x + 1 } = 2{ 2 + 1 }

⇒ x + 1 = 2 + 1

⇒ x = 2

Vậy x = 2

`x :3*5 = 3/4 :(-5/6)`

`x :15 =3/4*(-6/5)=-9/10`

`x = -9/10 *15 =-27/2`

`x-1*2/2 = 8/x -1.2`

`x- 1*1 = 8/x -2`

`x-8/x = -2+1`

`x-8/x =-1`

`x^2 -8x =-x`

`x^2 -8x +x=0`

`x^2 -7x =0`

`x(x-7) =0`

`=>[(x=0),(x=7):}`

`a, x \div 15=-9/10`

`x=-9/10*14`

`x=-27/2`

`b, (x-1*2)/2=8/(x-1*2)`

\(\left(x-1\cdot2\right)\cdot\left(x-1\cdot2\right)=8\cdot2\)

`(x-1*2)^2=16`

`(x-1*2)^2=(+-4)^2`

\(\Rightarrow\left[{}\begin{matrix}x-1\cdot2=4\\x-1\cdot2=-4\end{matrix}\right.\)

`=>`\(\left[{}\begin{matrix}x-2=4\\x-2=-4\end{matrix}\right.\)

`=>`\(\left[{}\begin{matrix}x=4+2\\x=\left(-4\right)+2\end{matrix}\right.\)

`=>`\(\left[{}\begin{matrix}x=6\\x=-2\end{matrix}\right.\)

a)

\(\begin{array}{l}x + \left( { - \frac{1}{5}} \right) = \frac{{ - 4}}{{15}}\\x = \frac{{ - 4}}{{15}} + \frac{1}{5}\\x = \frac{{ - 4}}{{15}} + \frac{3}{{15}}\\x = \frac{{ - 1}}{{15}}\end{array}\)                 

Vậy \(x = \frac{{ - 1}}{{15}}\).

b)

\(\begin{array}{l}3,7 - x = \frac{7}{{10}}\\x = 3,7 - \frac{7}{{10}}\\x = \frac{{37}}{{10}} - \frac{7}{{10}}\\x=\frac{30}{10}\\x = 3\end{array}\)

Vậy \(x = 3\).

c)

\(\begin{array}{l}x.\frac{3}{2} = 2,4\\x.\frac{3}{2} = \frac{{12}}{5}\\x = \frac{{12}}{5}:\frac{3}{2}\\x = \frac{{12}}{5}.\frac{2}{3}\\x = \frac{8}{5}\end{array}\)

Vậy \(x = \frac{8}{5}\)       

d)

\(\begin{array}{l}3,2:x =  - \frac{6}{{11}}\\\frac{{16}}{5}:x =  - \frac{6}{{11}}\\x = \frac{{16}}{5}:\left( { - \frac{6}{{11}}} \right)\\x = \frac{{16}}{5}.\frac{{ - 11}}{6}\\x = \frac{{ - 88}}{{15}}\end{array}\)

Vậy \(x = \frac{{ - 88}}{{15}}\).