x=1/6

x=1/4

a) x = 1/6

b) x = 1/4

HT

a) 2/3 + x = 5/6

X = 5/6 - 2/3

X = 1/6

b)  x : 5/6 = 3/10

X = 5/6 x 3/10

X = 17/15

a) Ta có: \(\left(2x-1\right)\left(x^2-x+1\right)=2x^3-3x^2+2\)

\(\Leftrightarrow2x^3-2x^2+2x-x^2+x-1-2x^3+3x^2-2=0\)

\(\Leftrightarrow3x=3\)

hay x=1

Vậy: S={1}

b) Ta có: \(\left(x+1\right)\left(x^2+2x+4\right)-x^3-3x^2+16=0\)

\(\Leftrightarrow x^3+2x^2+4x+x^2+2x+4-x^3-3x^2+16=0\)

\(\Leftrightarrow6x=-20\)

hay \(x=-\dfrac{10}{3}\)

c) Ta có: \(\left(x+1\right)\cdot\left(x+2\right)\left(x+5\right)-x^3-8x^2=27\)

\(\Leftrightarrow\left(x^2+3x+2\right)\left(x+5\right)-x^3-8x^2-27=0\)

\(\Leftrightarrow x^3+5x^2+3x^2+15x+2x+10-x^3-8x^2-27=0\)

\(\Leftrightarrow17x=17\)

hay x=1

\(a,\left(x-\dfrac{1}{2}\right):\dfrac{1}{3}+\dfrac{5}{7}=9\dfrac{5}{7}\)

\(\Leftrightarrow\left(x-\dfrac{1}{2}\right).3=\dfrac{68}{7}-\dfrac{5}{7}\)

\(\Leftrightarrow\left(x-\dfrac{1}{2}\right).3=9\)

\(\Leftrightarrow x-\dfrac{1}{3}=3\)

\(\Leftrightarrow x=3+\dfrac{1}{3}\)

\(\Leftrightarrow x=\dfrac{9}{3}+\dfrac{1}{3}\)

\(\Leftrightarrow x=\dfrac{10}{3}\)

\(b,x+30\%x=-1,31\)

\(\Leftrightarrow x+\dfrac{3}{10}.x=-\dfrac{131}{100}\)

\(\Leftrightarrow x.\left(1+\dfrac{3}{10}\right)=-\dfrac{131}{100}\)

\(\Leftrightarrow x.\dfrac{13}{10}=-\dfrac{131}{100}\)

\(\Leftrightarrow x=-\dfrac{131}{100}.\dfrac{10}{13}\)

\(\Leftrightarrow x=-\dfrac{131}{130}\)

\(c,-\dfrac{2}{3}x+\dfrac{1}{5}=\dfrac{1}{10}\)

\(\Leftrightarrow\dfrac{-2}{3}x=\dfrac{1}{10}-\dfrac{1}{5}\)

\(\Leftrightarrow\dfrac{-2}{3}x=\dfrac{1}{10}-\dfrac{2}{10}\)

\(\Leftrightarrow-\dfrac{2}{3}x=-\dfrac{1}{10}\)

\(\Leftrightarrow x=-\dfrac{1}{10}.\left(-\dfrac{3}{2}\right)\)

\(\Leftrightarrow x=\dfrac{3}{20}\)

a: \(\Leftrightarrow\left(x-1\right)^2=81\)

\(\Leftrightarrow\left[{}\begin{matrix}x-1=9\\x-1=-9\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=10\\x=-8\end{matrix}\right.\)

x - 2/3 = 3/5 - 1/4

x - 2/3 = 7/20

x = 7/20 + 2/3 

x = 61/60

- 2/3 . x + 1/5 = 1/10

-2/3 . x = 1/10 - 1/5

- 2/3 . x = -1/10

x = -1/10 : -2/3

x = 3/20

a)13,2 - x = -4,3

=> x = 13,2 - ( -4,3)

=> x = 17,5

b)x phần 3 = 20 phần 15 

\(\dfrac{x}{3}=\dfrac{20}{15}=>20.3=x.15=>60=x.15=>x=60:15=>x=4\)

c) 2 phần 3 - 1 phần 3 x = -5 phần 3 + 1 phần 2

Mong bạn viết lại đề giúp mình

d) x - 3 phần 5 = -7 phần 10

\(\dfrac{x-3}{5}=\dfrac{-7}{10}=>5.-7=\left(x-3\right).10=>-35=\left(x-3\right).10=>x-3=-35:10=>x-3=\text{-3,5}=>x=\text{-3,5}+3=>x=6,5\)

`a)`

`13,2-x=-4,3`

`x=13,2-(-4,3)`

`x=17,5`

Vậy `x=17,5`

__________________________

`b)`

\(\dfrac{x}{3}=\dfrac{20}{15}\)

`=>x` `xx15=20xx3`

`x` `xx15=60`

`x=60:15`

`x=4`

Vậy `x=4`

__________________________

`c)`

\(\dfrac{2}{3}-\dfrac{1}{3x}=\dfrac{-5}{3}+\dfrac{1}{2}\\ \dfrac{2}{3}-\dfrac{1}{3x}=-\dfrac{7}{6}\\ \dfrac{1}{3x}=\dfrac{2}{3}-\left(-\dfrac{7}{6}\right)\\ \dfrac{1}{3x}=\dfrac{11}{6}\\ \Rightarrow1\times6=11\times3\times x\\ 6=33\times x\\ x=5,5\)

Vậy `x=5,5`

__________________________

`d)`

\(\dfrac{x-3}{5}=\dfrac{-7}{10}\)

`=>(x-3)xx10=5xx(-7)`

`(x-3)xx10=-35`

`x-3=-35:10`

`x-3=-3,5`

`x=-6,5`

Vậy `x=-6,5`

`@An`

a: x=2/3-4/5=10/15-12/15=-2/15

b: 1/2-x=7/12

=>x=1/2-7/12=-1/12

c: =>7/2:x=-7/2

=>x=-1

d: =>1/6x=3/8-5/2=3/8-20/8=-17/8

=>x=-17/8*6=-102/8=-51/4

e: =>1,5x=-1,5

=>x=-1

tách đi bạn

a) (2x - 3)(6 - 2x) = 0

=> \(\left[{}\begin{matrix}2x-3=0\\6-2x=0\end{matrix}\right.=>\left[{}\begin{matrix}2x=3\\2x=6\end{matrix}\right.=>\left[{}\begin{matrix}x=\dfrac{3}{2}\\x=3\end{matrix}\right.\)

b) \(5\dfrac{4}{7}:x=13=>\dfrac{39}{7}:x=13=>x=\dfrac{39}{7}:13=>x=\dfrac{3}{7}\)

c) \(2x-\dfrac{3}{7}=6\dfrac{2}{7}=>2x-\dfrac{3}{7}=\dfrac{44}{7}=>2x=\dfrac{47}{7}=>x=\dfrac{47}{14}\)

d) \(\dfrac{x}{5}+\dfrac{1}{2}=\dfrac{6}{10}=>\dfrac{x}{5}=\dfrac{6}{10}-\dfrac{1}{2}=>\dfrac{x}{5}=\dfrac{1}{10}=>x.10=5=>x=\dfrac{1}{2}\)

e) \(\dfrac{x+3}{15}=\dfrac{1}{3}=>\left(x+3\right).3=15=>x+3=5=>x=2\)

f)\(\dfrac{x-12}{4}=\dfrac{1}{2}=\dfrac{x-12}{4}=\dfrac{2}{4}\)

⇒\(x-12=2\)

   \(x=2+12\)

  x = 14

g)2\(\dfrac{1}{4}.\left(x-7\dfrac{1}{3}\right)=1,5\)

\(\dfrac{9}{4}.\left(x-\dfrac{22}{3}\right)=1,5\) 

      \(\left(x-\dfrac{22}{3}\right)=\dfrac{3}{2}:\dfrac{9}{4}\)

       \(x-\dfrac{22}{3}=\dfrac{2}{3}\)

       \(x=\dfrac{2}{3}+\dfrac{22}{3}\) 

      \(x=8\)