a ) \(x\times3,9+x\times0,1=2,7\)

\(x\times\left(3,9+0,1\right)=x\times4=2,7\)

x = 2,7 : 4 = 0,675

b ) \(\frac{12,3}{x}-\frac{4,5}{x}=15=\frac{7,8}{x}\)

\(=7,8\div x=15\)

\(x=15\div7,8=\frac{15}{7,8}\)

X:10+Xx3,9=4,8

Xx0,1+Xx3,9=4,8

Xx(0,1+3,9)=4,8

Xx4=4,8

X=4,8:4

X=1,2

X : 10 + X x 3,9 = 4,8

X x 0,1 + X x 3,9 = 4,8

X x (0,1 + 3,9)     = 4,8

X x         5           = 4,8

              X           = 4,8 : 5

              X           =   0,96

10,6 : x + 7,19 : x = 3

( 10,6 + 7,19 ) : x = 3

17,79 : x = 3

x = 17,79 : 3

x = 5,93

x=5,93 nha

Vì 3,9 < 4 < 4,1

=> x = 4

Và x = 4,01

Đáp số : 4; 4,1

Ta có : 3,9 < x < 4,1

=> x= 3,92 ; 4

Đáp số : 3,92 và 4

k mk nha

thank you

x = 4

Hok tốt 

^^

Bài 5:

a)x+37=50

⇔x=13

b)2x-3=11

⇔2x=14

⇔x=7

c)(2+x):5=6

⇔2+x=30

⇔x=28

d)2+x:5=6

⇔x:5=4

⇔x=20

a)x+37=50
   x      =50-37
  x       =13
b)2.x-3=11
   2.x   =11+3
   2.x   =14
      x   =14:2
      x   =7
c)(2+x):5=6
   2+x =6.5
   2+x =30
  x=30-2
  x=28
d)2+x:5=6
   x:5=6-2
   x:5=4
   x=4.5
   x=20
Câu trả lời nhớ ghi đầy đủ như này nha bạn

   

d) Ta có: \(32\%-0.25:x=-\dfrac{17}{5}\)

\(\Leftrightarrow0.25:x=\dfrac{8}{25}+\dfrac{17}{5}=\dfrac{93}{25}\)

hay \(x=\dfrac{25}{372}\)

Vậy: \(x=\dfrac{25}{372}\)

e) Ta có: \(\left(x+\dfrac{1}{5}\right)^2+\dfrac{17}{25}=\dfrac{26}{25}\)

\(\Leftrightarrow\left(x+\dfrac{1}{5}\right)^2=\dfrac{9}{25}\)

\(\Leftrightarrow\left[{}\begin{matrix}x+\dfrac{1}{5}=\dfrac{3}{5}\\x+\dfrac{1}{5}=-\dfrac{3}{5}\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{2}{5}\\x=-\dfrac{4}{5}\end{matrix}\right.\)

Vậy: \(x\in\left\{\dfrac{2}{5};-\dfrac{4}{5}\right\}\)

f) Ta có: \(-\dfrac{32}{27}-\left(3x-\dfrac{7}{9}\right)^3=-\dfrac{24}{27}\)

\(\Leftrightarrow\left(3x-\dfrac{7}{9}\right)^3=\dfrac{-8}{27}\)

\(\Leftrightarrow3x-\dfrac{7}{9}=-\dfrac{2}{3}\)

\(\Leftrightarrow3x=\dfrac{1}{9}\)

hay \(x=\dfrac{1}{27}\)

g) Ta có: \(60\%\cdot x+0.4x+x:3=2\)

\(\Leftrightarrow\dfrac{4}{3}x=2\)

hay \(x=\dfrac{3}{2}\)

Vậy: \(x=\dfrac{3}{2}\)

h) PT \(\Leftrightarrow\left|\dfrac{20}{9}-x\right|=\dfrac{2}{9}\) \(\Rightarrow\left[{}\begin{matrix}\dfrac{20}{9}-x=\dfrac{2}{9}\\x-\dfrac{20}{9}=\dfrac{2}{9}\end{matrix}\right.\) \(\Leftrightarrow\left[{}\begin{matrix}x=2\\x=\dfrac{22}{9}\end{matrix}\right.\)

  Vậy ...

i) PT \(\Leftrightarrow\dfrac{8}{5}+\dfrac{2}{5}x=\dfrac{16}{5}\) \(\Leftrightarrow\dfrac{2}{5}x=\dfrac{8}{5}\) \(\Leftrightarrow x=4\)

  Vậy ...