a) 2/15-x = 3/10

<=> 45 - 3x = 20

<=> 3x = 45 - 20

<=> 3x = 25

<=> x = 25 : 3

<=> x = 25/3

Vậy x = 25/3

b) ( 10 - 4x ) + 120/2³ = 17

<=> ( 10 - 4x ) + 120/8 = 17

<=> ( 10 - 4x ) + 15 = 17

<=> 10 - 4x = 17 - 15

<=> 10 - 4x = 2

<=> 4x = 10 - 2

<=> 4x = 8

<=> x = 8 : 4

<=> x = 2

Vậy x = 2

7² x 5-(2x+1)=630:9

<=> 49 x 5-2x-1=70

<=> 245-2x-1=70

<=> -2x+244=70

<=> -2x=-174

<=> x=87

tìm x biết:

a, 7².5-(2x+1)=630:9     

    49.5-(2x+1)=70

    245-(2x+1)=70

    2x+1=245-70

    2x+1=175

    2x=175-1

    2x=174

      x=174:2

      x=87

Vậy x=87

b,  (10-4x)+120:2³=17    

     (10-4x)+120:8=17

     (10-4x)+15=17

       10-4x=17-15

       10-4x=2

            4x=10-2

            4x=8

              x=8:4

              x=2

Vậy x=2

a, 7².5-(2x+1)=630:9

 \(\Leftrightarrow\)   49.5-(2x+1)=70

  \(\Leftrightarrow\)   245 - (2x+1) = 70

     \(\Leftrightarrow\)          2x + 1 = 245 - 70

      \(\Leftrightarrow\)        2x + 1  = 175

   \(\Leftrightarrow\)          2x         = 175 - 1

      \(\Leftrightarrow\)      2x          = 174

        \(\Leftrightarrow\)     x           = 174 : 2

      \(\Leftrightarrow\)       x           = 87.

Vậy x = 87.

b,  (10-4x)+120:2³=17   

 \(\Leftrightarrow\)     (10-4x)+120:8 = 17

    \(\Leftrightarrow\)  (10-4x)+15       = 17

\(\Leftrightarrow\)       10 - 4x             = 17 - 15

  \(\Leftrightarrow\)     10 - 4x              = 2

   \(\Leftrightarrow\)           4x              = 10 - 2

      \(\Leftrightarrow\)       4x               = 8

    \(\Leftrightarrow\)          x                = 8 : 4

  \(\Leftrightarrow\)           x                 = 2

Vậy x = 2.

# HOK TỐT #

a) 52x - 3 - 2 . 52 = 52 . 3

x - 3/52 - 2 = 3

x = 3 + 2 + 3/52

x = 263/52

b) 740 / (x + 10) = 102 - 2 . 13

740 / (x + 10) = 76

x + 10 = 740 / 76

x + 10 = 185/19

x = 185/19 - 10

x = -5/19

c) 65 - 4x + 2 = 20140

65 - 4x = 20140 - 2

65 - 4x = 20138

4x = 65 - 20138

4x = -20073

x = -20073/4

d) 120 + 2 . (3x - 17) = 214

60 + 3 . x - 17 = 107

20 + x - 17/3 = 107/3

20 + x = 107/3 + 17/3

20 + x = 124/3

x = 124/3 - 20

x = 64/3

e) 41 - 2x + 1 = 9

42 - 2x = 9

21 - x = 9/2

x = 21 - 9/2

x = 33/2

\(\left(10-4x\right)+120\div2^3=17\)

\(\left(10-4x\right)+120\div8=17\)

\(\left(10-4x\right)+15=17\)

\(10-4x=17-15\)

\(10-4x=2\)

\(4x=10-2\)

\(4x=8\)

\(x=8\div4\)

\(x=2\)

(10-4x)+120:2^3=17

(10-4x)+120= 17.2^3

(10-4x)+120=17.8

(10-4x)+120=136

10-4x= 136-120

10-4x= 16

4x= 10-16

4x=10+(-16)

4x=-6

x= -6:4

x=-1,5

(10-4x)+120 : 2^3=17

(10-4x)+120 : 8   =17

(10-4x)+120        =17.8

(10-4x)+120        =136

10-4x                 =136-120

10-4x       =16

    4x        =10-16

    4x        = -6

      x        =-6:4

      x        = -1,5

nhớ tk cho mình vs nha

thank you

a) \(8x+56:14=60\)

\(\Rightarrow8x+4=60\)

\(\Rightarrow8x=56\)

\(\Rightarrow x=\dfrac{56}{8}\)

\(\Rightarrow x=7\)

b) Mình làm rồi nhé !

c) \(41-2^{x+1}=9\)

\(\Rightarrow2^{x+1}=41-9\)

\(\Rightarrow2^{x+1}=32\)

\(\Rightarrow2^{x+1}=2^5\)

\(\Rightarrow x+1=5\)

\(\Rightarrow x=4\)

d) \(3^{2x-4}-x^0=8\)

\(\Rightarrow3^{2x-4}-1=8\)

\(\Rightarrow3^{2x-4}=9\)

\(\Rightarrow3^{2x-4}=3^2\)

\(\Rightarrow2x-4=2\)

\(\Rightarrow2x=6\)

\(\Rightarrow x=3\)

g) \(65-4^{x+2}=2014^0\)

\(\Rightarrow65-4^{x+2}=1\)

\(\Rightarrow4^{x+2}=64\)

\(\Rightarrow4^{x+2}=4^3\)

\(\Rightarrow x+2=3\)

\(\Rightarrow x=1\)

i) \(120+2\left(4x-17\right)=214\)

\(\Rightarrow2\left(4x-17\right)=214-120\)

\(\Rightarrow2\left(4x-17\right)=94\)

\(\Rightarrow4x-17=47\)

\(\Rightarrow4x=47+17\)

\(\Rightarrow4x=64\)

\(\Rightarrow x=16\)

a: \(8x+56:14=60\)

=>8x+4=60

=>8x=60-4=56

=>x=56/8=7

b: \(5^{2x-3}-2\cdot5^2=5^2\cdot3\)

=>\(5^{2x-3}=5^2\cdot3+2\cdot5^2=5^3\)

=>2x-3=3

=>2x=6

=>x=3

c: \(41-2^{x+1}=9\)

=>\(2^{x+1}=41-9=32\)

=>x+1=5

=>x=4

d: \(3^{2x-4}-x^0=8\)

=>\(3^{2x-4}-1=8\)

=>\(3^{2x-4}=8+1=9\)

=>2x-4=2

=>2x=6

=>x=3

g: \(65-4^{x+2}=2014^0\)

=>\(65-4^{x+2}=1\)

=>\(4^{x+2}=65-1=64\)

=>x+2=3

=>x=1

i: 120+2(4x-17)=214

=>2(4x-17)=214-120=94

=>4x-17=94/2=47

=>4x=64

=>\(x=\dfrac{64}{4}=16\)

b)x=2/15-3/10=-1/6
 

a: \(4x^3+12=120\)

=>\(4x^3=108\)

=>\(x^3=27=3^3\)

=>x=3

b: \(\left(x-4\right)^2=64\)

=>\(\left[{}\begin{matrix}x-4=8\\x-4=-8\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=12\\x=-4\end{matrix}\right.\)

c: (x+1)^3-2=5^2

=>\(\left(x+1\right)^3=25+2=27\)

=>x+1=3

=>x=2

d: 136-(x+5)^2=100

=>(x+5)^2=36

=>\(\left[{}\begin{matrix}x+5=6\\x+5=-6\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=1\\x=-11\end{matrix}\right.\)

e: \(4^x=16\)

=>\(4^x=4^2\)

=>x=2

f: \(7^x\cdot3-147=0\)

=>\(3\cdot7^x=147\)

=>\(7^x=49\)

=>x=2

g: \(2^{x+3}-15=17\)

=>\(2^{x+3}=32\)

=>x+3=5

=>x=2

h: \(5^{2x-4}\cdot4=10^2\)

=>\(5^{2x-4}=\dfrac{100}{4}=25\)

=>2x-4=2

=>2x=6

=>x=3

i: (32-4x)(7-x)=0

=>(4x-32)(x-7)=0

=>4(x-8)*(x-7)=0

=>(x-8)(x-7)=0

=>\(\left[{}\begin{matrix}x-8=0\\x-7=0\end{matrix}\right.\)

=>\(\left[{}\begin{matrix}x=8\\x=7\end{matrix}\right.\)

k: (8-x)(10-2x)=0

=>(x-8)(x-5)=0

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

m: \(3^x+3^{x+1}=108\)

=>\(3^x+3^x\cdot3=108\)

=>\(4\cdot3^x=108\)

=>\(3^x=27\)

=>x=3

n: \(5^{x+2}+5^{x+1}=750\)

=>\(5^x\cdot25+5^x\cdot5=750\)

=>\(5^x\cdot30=750\)

=>\(5^x=25\)

=>x=2

a) 72,5 - (2x + 1) = 630 : 9

⇒ 72,5 - (2x + 1) = 70

⇒ 2x + 1 = 2,5

⇒ 2x = 1,5

⇒ x = 0,75

b) (10 - 4x) + 120 : 2³ = 17

⇒ (10 - 4x) + 120 : 8 = 17

⇒ (10 - 4x) + 15 = 17

⇒ 10 - 4x = 2

⇒ 4x = 8

⇒ x = 2

Vậy x = 2

c) [124 - (20 - 4x)] : 30 + 7 = 11

⇒ [124 - (20 - 4x)] : 30 = 4

⇒ 124 - (20 - 4x) = 120

⇒ 20 - 4x = 4

⇒ 4x = 16

⇒ x = 4

Vậy x = 4

TBR, Ta có: 

(100 – 4x) + 120 : 2³ = 1 + 4²  

 \(\Rightarrow\) 10 – 4x + 15 = 17

        = 25 – 4x = 17 \(\Rightarrow\)  4x = 25 – 17 \(\Rightarrow\) 4x = 25 – 17

\(\Rightarrow\)  4x = 8  \(\Rightarrow\)x = 8 : 4 = 2

\(\left(10-4x\right)+120:2^3=1+4^2\)

\(\Rightarrow\) \(\left(10-4x\right)+120:8=17\)

\(\Rightarrow\) \(\left(10-4x\right)+15=17\)

\(\Rightarrow\) \(10-4x=2\)

\(\Rightarrow\) \(4x=8\)

\(\Rightarrow\) \(x=2\)

(10 - 4x) + 120 : 2³ = 1 + 4²

(10 - 4x) + 120 : 2³ = 1 + 16 = 17

(10 - 4x) + 120 : 8 = 17

(10 - 4x) +   15      = 17

10 - 4x                   = 17 - 15 = 2

       4x                   = 10 - 2 = 8

         x                   = 8 : 4

         x                   = 2

Vậy x = 2

Good Luck!