x/30 + 4/5= 79/30

x/30 = 79/30 - 4/5

x/30= 11/6

11/6= 55/30

=> x= 55

a,17-3x-11=31-2x

=>  6 - 3x = 31 - 2x 

=> 6 - 31 = - 2x + 3x

=> x = - 25

Vậy x = - 25

b,12 - | x + 3 |=5

=> | x + 3 | = 7 

\(\Rightarrow\orbr{\begin{cases}x+3=7\\x+3=-7\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=4\\x=-10\end{cases}}\)

Vậy \(x\in\left\{4;-10\right\}\)

c,4 x+ (-46) = -30

=> 4x =  - 30 + 46 

=> 4x = 16

=> x = 4

Vậy x = 4

d,   -20 + (5x - 5 ) = 60

= > - 20 + 5x - 5 = 60

=> 5x = 60 + 20 + 5

=> 5x = 85

=> x = 17

Vậy x = 17

e,   10 + |1 - 2x |= 15

=> | 1 - 2x | = 5

\(\Rightarrow\orbr{\begin{cases}1-2x=5\\1-2x=-5\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}2x=-4\\2x=6\end{cases}}\)

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

Vậy \(x\in\left\{-2;3\right\}\)

Dài qua lần sau đừng đăng nhiều như v

Tự nghĩ k đc à

@@ Học tốt @@

## Chiyuki Fujito

X=4/15:2/5=2/3

2/3

X = 4/5 : 2/15

X = 2/3

1) 14x-8x=10+5

x(14-8)=15

x6=15

x=15/6

2)5x-3x=30-15

2x=15

x=15/2

3)làm tương tự

1) x=2,5

2) x=7,5

3) x=4

4) x=7/3

5) x=8,25

11: Ta có: \(\left(x+3\right)^3=125\)

\(\Leftrightarrow x+3=5\)

hay x=2

12: Ta có: \(\left(2x\right)^4=16\)

\(\Leftrightarrow x^4=1\)

hay \(x\in\left\{1;-1\right\}\)

11: Ta có: \left(x+3\right)^3=125(x+3)3=125

$\iff x+3=5$

hay x=2

12: Ta có: \left(2x\right)^4=16(2x)4=16

\Leftrightarrow x^4=1(2x)   = 2   =2  4

           4      

⇔2x=2⇔ x=1

13) 32:(3x-2)=2^3

32:(3x-2)=8

3x-2=32:8=4

3x=4+2=6

x=6:3=2

⇔x=2

x:x+9<xX5<20

1+9<xX5<20

10<xX5<20

2X5<xX5<4X5

x=3

=98 nha ban

X=3 nha bạn

câu a:

2x=3+(-1)

2x=2

x=1

câu b

x+1=-3+5

x+1=2

x=1

câu c

x-2=5-4

x-2=1

x=1+2=3

*còn lại tương tự

a)10-(5-x)=15

5-x=10-15

x=5-(-5)

x=10

b)20-(10-x)=30

10-x=20-30

x=10-(-10)

x=20

a ) 10 - ( 5 - x ) = 15

            ( 5- x )  = 10 - 15

            5 - x     =  - 5

               x       = ( - 5 ) - 5

                x      = 0

b )  20 - ( 10 - x ) = 30 

            ( 10 - x )  = 20 - 30

            ( 10 - x )  =  - 10

                  x       = ( - 10 ) - 10 

                   x      = 0

\(\dfrac{x}{5}=\dfrac{5}{6}-\dfrac{19}{30}\)

\(\Leftrightarrow\dfrac{x}{5}=\dfrac{25}{30}-\dfrac{19}{30}=\dfrac{6}{30}=\dfrac{1}{5}\)

\(\Leftrightarrow x=1\)

Ta có : \(\dfrac{x}{5}=\dfrac{5}{6}+\left(-\dfrac{19}{30}\right)=\dfrac{25}{30}-\dfrac{19}{30}=\dfrac{1}{5}\)

\(\Leftrightarrow5x=5\)

\(\Leftrightarrow x=1\)

Vậy ...

Ta có: \(\dfrac{x}{5}=\dfrac{5}{6}-\dfrac{19}{30}\)

\(\Leftrightarrow\dfrac{x}{5}=\dfrac{25}{30}-\dfrac{19}{30}\)

\(\Leftrightarrow\dfrac{x}{5}=\dfrac{6}{30}=\dfrac{1}{5}\)

hay x=1

Vậy: x=1

1) 4x-(2x-5)=21

4x-2x+5=21

2x+5=21

2x=21 -5

2x=16

x=16/2

x=8

2)14x+5=8x+10

14x-8x=10-5

6x=5

x=5/6

3) 15+5x=3x+30

5x-3x=30-15

2x=15

x=15/2

Vậy x=15/2