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a: \(\Leftrightarrow\dfrac{x}{-4}=\dfrac{21}{y}=\dfrac{z}{-80}=\dfrac{3}{4}\)

=>x=-3; y=28; z=-60

b: 5/12=x/-72

=>x=-72*5/12=-6*5=-30

c: =>x+3=-5

=>x=-8

21 tháng 2 2023

` 8/23 . 46/24 =1/3 .x`

`=>8/23 . 23/12 =1/3 . x`

`=> 1/3 . x=2/3`

`=>x=2/3 : 1/3`

`=>x=2/3 . 3`

`=> x= 6/3`

`=>x=2`

`----`

`1/5 : x= 1/5-1/7`

`=>1/5 : x=  7/35 - 5/35`

`=> 1/5 :x= 2/35`

`=>x= 1/5 : 2/35`

`=>x=1/5 . 35/2`

`=>x=7/2`

`----`

`4/9 - (x-1/2)^2 =1/3`

`=> (x-1/2)^2 =4/9-1/3`

`=> (x-1/2)^2 =4/9- 3/9`

`=> (x-1/2)^2 =1/9`

`=> (x-1/2)^2 = (+- 1/3)^2`

`@ TH1`

`x-1/2=1/3`

`=>x=1/3+1/2`

`=>x= 2/6 + 3/6`

``=>x= 5/6`

`@ TH2`

`x-1/2=-1/3`

`=>x=-1/3 +1/2`

`=>x= -2/6 + 3/6`

`=>x=1/6`

`----`

`3,2 . x-(4/5+2/3) : 3 2/3 = 7/10`

`=> 3,2 . x-22/15 : 11/3 = 7/10`

`=>  3,2 . x-22/15 = 7/10 . 11/3`

`=>  3,2 . x-22/15 =77/30`

`=> 3,2 .x= 77/30 + 22/15`

`=> 3,2 .x=121/30`

`=>x= 121/30. 5/16`

`=>x= 121/96`

21 tháng 1 2022

\(a,\left(2x-5\right)+17=6\\ \Rightarrow2x-5=-11\\ \Rightarrow2x=-6\\ \Rightarrow x=-3\\ b,10-2\left(4-3x\right)=-4\\ \Rightarrow2\left(4-3x\right)=14\\ \Rightarrow4-3x=7\\ \Rightarrow3x=-3\\ \Rightarrow x=-1\\ c,24:\left(3x-2\right)=-3\\ \Rightarrow3x-2=-8\\ \Rightarrow3x=-6\\ \Rightarrow x=-2\\ d,5-2x=-17+12\\ \Rightarrow5-2x=-5\\ \Rightarrow2x=10\\ \Rightarrow x=5\)

a: =>2x-5=-11

=>2x=-6

hay x=-3

b: =>2(4-3x)=14

=>4-3x=7

=>3x=-3

hay x=-1

c: =>3x-2=-8

=>3x=-6

hay x=-2

a: =>x/-3=3

hay x=-9

b: =>x/9=-1/9

hay x=-1

c: =>x+1/5=-1/3

hay x=-8/15

d: =>-7/x=-7/9

hay x=9

14 tháng 2 2022

a, \(\dfrac{x}{-3}=3\Leftrightarrow x=-9\)

b, \(\dfrac{x}{9}=-\dfrac{1}{9}\Rightarrow x=-1\)

c, \(\dfrac{x+3}{15}=-\dfrac{6}{15}\Rightarrow x=-9\)

d, \(\dfrac{42}{-54}=-\dfrac{42}{6x}\Rightarrow6x=54\Leftrightarrow x=9\)

24 tháng 7 2021

a) \(\left(2\dfrac{3}{4}-1\dfrac{4}{5}\right)\cdot x=1\)

\(\left(\dfrac{11}{4}-\dfrac{9}{5}\right)\cdot x=1\)

\(\dfrac{19}{20}x=1\)

\(x=\dfrac{20}{19}\)

Vậy \(x=\dfrac{20}{19}\)

24 tháng 7 2021

b) \(\left(x^2-9\right)\left(3-5x\right)=0\)

TH1:

\(x^2-9=0\)

\(x^2=9\)

\(x^2=3^2=\left(-3\right)^2\)

=>\(x\in\left\{3;-3\right\}\)

TH2:

\(3-5x=0\)

\(5x=3\)

\(x=\dfrac{3}{5}\)

Vậy \(x\in\left\{3;-3;\dfrac{3}{5}\right\}\)

 

AH
Akai Haruma
Giáo viên
9 tháng 5 2021

Lời giải:

a) 

$\frac{4}{7}x=\frac{2}{3}+\frac{1}{5}=\frac{13}{15}$

$x=\frac{13}{15}:\frac{4}{7}=\frac{91}{60}$

b) 

$\frac{5}{7}:x=\frac{1}{6}-\frac{4}{5}$

$\frac{5}{7}:x=\frac{-19}{30}$

$x=\frac{5}{7}:\frac{-19}{30}=\frac{-150}{133}$

a) \(\dfrac{4}{7}.x-\dfrac{2}{3}=\dfrac{1}{5}\) 

            \(\dfrac{4}{7}.x=\dfrac{1}{5}+\dfrac{2}{3}\) 

            \(\dfrac{4}{7}.x=\dfrac{13}{15}\) 

                \(x=\dfrac{13}{15}:\dfrac{4}{7}\) 

                \(x=\dfrac{91}{60}\) 

b) \(\dfrac{4}{5}+\dfrac{5}{7}:x=\dfrac{1}{6}\) 

            \(\dfrac{5}{7}:x=\dfrac{1}{6}-\dfrac{4}{5}\) 

            \(\dfrac{5}{7}:x=\dfrac{-19}{30}\) 

                  \(x=\dfrac{5}{7}:\dfrac{-19}{30}\) 

                 \(x=\dfrac{-150}{133}\)

HQ
Hà Quang Minh
Giáo viên
7 tháng 10 2023

 a) \(1\frac{2}{7} = 1 + \frac{2}{7} = \frac{9}{2}\)

\(\begin{array}{l}x:1\frac{2}{7} =  - 3,5\\x:\frac{9}{7} =  - \frac{7}{2}\\x =  - \frac{7}{2}.\frac{9}{7}\\x =  - \frac{9}{2}\end{array}\)

b) \(0,4.x - \frac{1}{5}.x = \frac{3}{4}\)

\(\begin{array}{l}\frac{2}{5}.x - \frac{1}{5}.x = \frac{3}{4}\\\left( {\frac{2}{5} - \frac{1}{5}} \right).x = \frac{3}{4}\\\frac{1}{5}.x = \frac{3}{4}\\x = \frac{3}{4}:\frac{1}{5}\\x = \frac{3}{4}.5\\x = \frac{{15}}{4}\end{array}\)

a: x=81-257=-176

b: x=-35+546=511

c: x=721+615=1336

d: x=-500:25=-20

e: x=-15*5=-75

f: x=612/9=68