a.\(x+\dfrac{4}{7}=\dfrac{38}{21}\)

\(x=\dfrac{38}{21}-\dfrac{4}{7}\)

\(x=\dfrac{38}{21}-\dfrac{12}{21}=\dfrac{26}{21}\)

b.\(x-\dfrac{1}{3}=\dfrac{7}{45}:\dfrac{2}{15}\)

\(x-\dfrac{1}{3}=\dfrac{7}{6}\)

\(x=\dfrac{7}{6}+\dfrac{1}{3}\)

\(x=\dfrac{7}{6}+\dfrac{2}{6}=\dfrac{9}{6}\)

x = 38/21 - 4/7

x = 26/21

x - 1/3 = 7/6

x = 7/6 + 1/3

x = 3/2

a) x = 5/8 : 3/4

x = 5/6

b) x = 5/6 - 1/12

x = 3/4

a)x=\(\dfrac{5}{8}:\dfrac{3}{4}=\dfrac{5}{6}\)

b) x=\(\dfrac{5}{6}-\dfrac{1}{12}=\dfrac{3}{4}\)

a \(x=\dfrac{5}{8}:\dfrac{3}{4}\)

\(x=\dfrac{5}{8}\times\dfrac{4}{3}\)

\(x=\dfrac{5}{6}\)

b \(x=\dfrac{5}{6}-\dfrac{1}{12}\)

\(x=\dfrac{10}{12}-\dfrac{1}{12}\)

\(x=\dfrac{9}{12}\)

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

a) \(\dfrac{x.2}{-15}=\dfrac{-5}{3}\)

\(\dfrac{x.2}{-15}=\dfrac{25}{-15}\)

x.2=25

x=12,5

b) \(\dfrac{x-1}{-12}=\dfrac{-3}{x-1}\)

(x-1)²=-3.(-12)

(x-1)²=36 

⇒(x-1)²\(\Rightarrow\left[{}\begin{matrix}x-1=6\\x-1=-6\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=7\\x=-5\end{matrix}\right.\)

a: x=12

b: x=-19

c)x=-25

d)x=30

a) (x + 3)^2 - 4x - 12 = 0

<=> (x + 3)^2 - 4(x + 3) = 0

<=> (x + 3)(x - 1) = 0

<=> x = -3 hoặc x = 1

b) x(x + 5)(x- 5) - (x - 3)(x^2 + 3x + 9) = 7

<=> x^3 - 25x - x^3 + 27 = 7

<=> -25x + 27 = 7

<=> x = 4/5

a/ \(\left(x+3\right)^2-4x-12=0\)

\(\left(x+3\right)^2-4\left(x+3\right)=0\)

\(\left(x+3\right)\left(x+3-4\right)=0\)

\(\left[{}\begin{matrix}x+3=0\Rightarrow x=-3\\x+3-4=0\Rightarrow x=1\end{matrix}\right.\)

---

b/ \(x\left(x+5\right)\left(x-5\right)-\left(x-3\right)\left(x^2+3x+9\right)=7\)

\(x\left(x^2-25\right)-\left(x^3-27\right)=7\)

\(x^3-25x-x^3+27=7\)

\(-25x=-20\)

\(x=\dfrac{20}{25}=\dfrac{4}{5}\)

a, <=>x² +6x+9-4x-12=0

<=> x² +2x -3=0

<=> x² +3x -x-3=0

<=> x.(x+3) - (x+3) =0

<=> (x-1)(x+3)=0

<=> x=1 hoặc x=-3

b, <=> x(x² -25) - (x-3)(x+3)² -7=0 

<=> x³ -25x + (9-x²) (x+3) -7=0

<=> x³ -25x+ 9x+27-x³ -3x² -7=0

<=> -3x² -16x +20=0

<=>(3x-10)(x-2) =0 (đoạn này tự phân tích nha ^ ^)

<=> x= 10/3 hoặc x=2

Chúc bạn học tốt nha!

a) \(\sqrt{x^2}=7\)⇒\(\left(\sqrt{x^2}\right)^2=49\)⇒x=7 hoặc -7

b) \(\sqrt{x^2}=8\)⇒\(\left(\sqrt{x^2}\right)=64\)⇒x=8 hoặc -8

c) \(\sqrt{4x^2}=6\)⇒\(\left(\sqrt{\left(2x\right)^2}\right)^2=36\)⇒x=3 hoặc -3

d) \(\sqrt{9x^2}=\left|-12\right|\)⇒\(\left(\sqrt{\left(3x\right)^2}\right)^2=144\)⇒x=12 hoặc -12

a. \(\sqrt{x^2}=7\)

<=> \(|x|=7\)

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

b. \(\sqrt{x^2}=8\)

<=> \(|x|=8\)

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

c. \(\sqrt{4x^2}=6\)

<=> \(|2x|=6\)

<=> \(\left[{}\begin{matrix}2x=6\\2x=-6\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=3\\x=-3\end{matrix}\right.\)

a) \(\left(12-12\dfrac{1}{3}\right):x+\dfrac{1}{6}=-\dfrac{2}{3}\)

\(-\dfrac{1}{3}x=-\dfrac{2}{3}-\dfrac{1}{6}\)

\(-\dfrac{1}{3}x=-\dfrac{5}{6}\)

\(x=-\dfrac{5}{6}:\left(-\dfrac{1}{3}\right)\)

\(x=\dfrac{5}{2}\)

b) \(\dfrac{4}{x}=\dfrac{x}{16}\)

\(x^2=4.16\)

\(x^2=64\)

\(\Rightarrow x=8;x=-8\)

`a)=>(12-37/3):x+1/6=-2/3`

`=>(12-37/3):x=-5/6`

`=>(-1/3):x=-5/6`

`=>x=(-1/3):(-5/6)`

`=>x=6/15=2/5`

`b)4/x=x/16`

`=>x^2=4*16`

`=>x^2=64`

`=>x^2=(+-8)^2`

1) \(\left(x-273\right)\times38=0\)

\(\Rightarrow x-273=0:38\)

\(\Rightarrow x-273=0\)

\(\Rightarrow x=0+273\)

\(\Rightarrow x=273\)

Vậy x = 273

2) \(\left(179-x\right)-12=57\)

\(\Rightarrow179-x=57+12\)

\(\Rightarrow179-x=69\)

\(\Rightarrow x=179-69\)

\(\Rightarrow x=110\)

Vậy x = 110

3) \(x-105:21=15\)

\(\Rightarrow x-5=15\)

\(\Rightarrow x=15+5\)

\(\Rightarrow x=20\)

Vậy x = 20

4) \(\left(x-105\right):21=15\)

\(\Rightarrow x-105=15\times21\)

\(\Rightarrow x-105=315\)

\(\Rightarrow x=315+105\)

\(\Rightarrow x=420\)

Vậy x = 420

_Chúc bạn học tốt_

 1. (x - 273).38 = 0

=> x - 273 = 0

=> x = 0 + 273

=> x = 273

vậy_