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3 tháng 12 2016

-3x-5=-7-13

-3x-5=(-20)

-3x=(-20)+5

-3x=(-15)

x=(-15):(-3)

x=5

11 tháng 5 2021

a)5-(13-3x)=109-(32+109)

   5-(13-3x)=-32

       13-3x  =37

            3x  =-24

            3x  =-6

a)5-(13-3x)=109-(32+109)

   5-13+3x  =109-32-109

         -8+3x=-32

              3x=-32-(-8)

              3x=-24

                x=-24:3

                x=-8

b)|3x-6|+(x-22)=0

   (3x-6)+(x-22)=0

        3x-6+x-22=0

                3x+x=0+6+22

                    4x=10

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

c)/7-2x/=-13-5.(-8)

   |7-2x|=27

⇒7-2x=27 hoặc 7-2x=-27

        x=-10 hoặc x=-17

15 tháng 3 2017

\(a,\frac{7}{3}x+5=\frac{9}{6}x-7\)

\(\frac{7}{3}x-\frac{9}{6}x=-7-5\)

  \(\left(\frac{7}{3}-\frac{9}{6}\right).x=-12\)

                  \(\frac{5}{6}.x=-12\)

                        \(x=\left(-12\right):\frac{5}{6}\)

                        \(x=-\frac{72}{5}\)

\(b,3x+\frac{6}{4}=5-\frac{7x}{6}\)

\(3x+\frac{7x}{6}=5-\frac{6}{4}\)

\(\left(3+\frac{7}{6}\right).x=\frac{7}{2}\)

\(\frac{25}{6}.x=\frac{7}{2}\)

\(x=\frac{7}{2}:\frac{25}{6}\)

\(x=\frac{21}{25}\)

\(c,\frac{12}{5}x+6=\frac{17}{3}x+12\)

\(\frac{12}{5}x-\frac{17}{3}x=12-6\)

            \(-\frac{49}{15}x=6\)

                       \(x=6:\left(-\frac{49}{15}\right)\)

                       \(x=-\frac{90}{49}\)

\(d,6\left(3x+7\right)=12\left(2x-4\right)\)

       \(18x+42=24x-48\)

     \(18x-24x=-48-42\)

                 \(-6x=-90\)

                        \(x=15\)

\(e,13\left(2x-9\right)=8\left(3x-13\right)\)

      \(26x-117=24x-104\)

      \(26x-24x=-104+117\)

                      \(2x=13\)

                        \(x=\frac{13}{2}\)

            

18 tháng 4 2023

\(1,-\dfrac{4}{7}+\dfrac{2}{3}\times\dfrac{-9}{14}\)

\(=\dfrac{-4}{7}+\dfrac{-18}{42}\)

\(=\dfrac{-4\times6}{7\times6}+\dfrac{-18}{42}\)

\(=\dfrac{-20}{42}+\dfrac{-18}{42}\)

\(=-\dfrac{38}{42}\)

\(=-\dfrac{19}{21}\)

\(2,\dfrac{17}{13}-\left(\dfrac{4}{13}-11\right)\)

\(=\dfrac{17}{13}-\dfrac{4}{13}+11\)

\(=\dfrac{13}{13}+11\)

\(=1+11\)

\(=12\)

\(3,8\dfrac{2}{7}-\left(3\dfrac{4}{9}+4\dfrac{2}{7}\right)\)

\(=\dfrac{58}{7}-\left(\dfrac{31}{9}+\dfrac{30}{7}\right)\)

\(=\dfrac{58}{7}-\dfrac{31}{9}-\dfrac{30}{7}\)

\(=\dfrac{58}{7}-\dfrac{30}{7}-\dfrac{31}{9}\)

\(=\dfrac{28}{7}-\dfrac{31}{9}\)

\(=\dfrac{28\times9}{7\times9}-\dfrac{31\times7}{9\times7}\)

\(=\dfrac{252}{63}-\dfrac{217}{63}\)

\(=\dfrac{35}{63}\)

\(=\dfrac{5}{9}\)

\(5,\left(\dfrac{2}{3}-1\dfrac{1}{2}\right):\dfrac{4}{3}+\dfrac{1}{2}\)

\(=\left(\dfrac{2}{3}-\dfrac{3}{2}\right):\dfrac{4}{3}+\dfrac{1}{2}\)

\(=\left(\dfrac{2\times2}{3\times2}-\dfrac{3\times3}{2\times3}\right):\dfrac{4}{3}+\dfrac{1}{2}\)

\(=\left(\dfrac{4}{6}-\dfrac{9}{6}\right):\dfrac{4}{3}+\dfrac{1}{2}\)

\(=\dfrac{-5}{6}:\dfrac{4}{3}+\dfrac{1}{2}\)

\(=\dfrac{-5}{6}\times\dfrac{3}{4}+\dfrac{1}{2}\)

\(=\dfrac{-15}{24}+\dfrac{1}{2}\)

\(=\dfrac{-15}{24}+\dfrac{1\times12}{2\times12}\)

\(=\dfrac{-15}{24}+\dfrac{12}{24}\)

\(=\dfrac{-3}{24}\)

\(=-\dfrac{1}{8}\)

\(6,\dfrac{-5}{13}+\dfrac{2}{5}+\dfrac{-8}{13}+\dfrac{3}{5}-\dfrac{3}{7}\)

\(=\left(\dfrac{-5}{13}+\dfrac{-8}{13}\right)+\left(\dfrac{2}{5}+\dfrac{3}{5}\right)-\dfrac{3}{7}\)

\(=\dfrac{-13}{13}+\dfrac{5}{5}-\dfrac{3}{7}\)

\(=-1+1-\dfrac{3}{7}\)

\(=-\dfrac{3}{7}\)

\(7,\dfrac{6}{5}\times\dfrac{3}{7}+\dfrac{6}{5}:\dfrac{7}{10}+\dfrac{6}{5}\)

\(=\dfrac{6}{5}\times\dfrac{3}{7}+\dfrac{6}{5}\times\dfrac{10}{7}+\dfrac{6}{5}\)

\(=\dfrac{6}{5}\times\left(\dfrac{3}{7}+\dfrac{10}{7}+1\right)\)

\(=\dfrac{6}{5}\times\left(\dfrac{3}{7}+\dfrac{10}{7}+\dfrac{1\times7}{1\times7}\right)\)

\(=\dfrac{6}{5}\times\left(\dfrac{3}{7}+\dfrac{10}{7}+\dfrac{7}{7}\right)\)

\(=\dfrac{6}{5}\times\dfrac{20}{7}\)

\(=\dfrac{120}{35}\)

\(=\dfrac{24}{7}\)

 

18 tháng 10 2020

Bài 1:

a) Ta có: \(82-7\left(3x-4\right)=47\)

\(\Leftrightarrow82-21x+28-47=0\)

\(\Leftrightarrow-21x+63=0\)

\(\Leftrightarrow-21x=-63\)

hay x=3(nhận)

Vậy: x=3

b) Ta có: \(97+4\left(5x-7\right)=129\)

\(\Leftrightarrow97+20x-28-129=0\)

\(\Leftrightarrow20x-60=0\)

\(\Leftrightarrow20x=60\)

hay x=3(nhận)

Vậy: x=3

c) Ta có: \(\left(7x-13\right)\cdot27-12=15\)

\(\Leftrightarrow189x-351-12-15=0\)

\(\Leftrightarrow189x-378=0\)

\(\Leftrightarrow189x=378\)

hay x=2(nhận)

Vậy: x=2

d) Ta có: \(\left(2x+3\right)\cdot13+23=140\)

\(\Leftrightarrow26x+39+23-140=0\)

\(\Leftrightarrow26x-78=0\)

\(\Leftrightarrow26x=78\)

hay x=3(nhận)

Vậy: x=3

đ) Ta có: \(52x+8x-5x=70\)

\(\Leftrightarrow55x=70\)

\(\Leftrightarrow x=\frac{70}{55}\)(loại)

Vậy: x∈∅

e) Ta có: \(19x-3x-x=60\)

\(\Leftrightarrow15x=60\)

hay x=4(nhận)

Vậy: x=4

g) Ta có: \(7\left(3x+1\right)-5\left(3x+1\right)=74\)

\(\Leftrightarrow2\left(3x+1\right)=74\)

\(\Leftrightarrow3x+1=37\)

\(\Leftrightarrow3x=36\)

hay x=12(nhận)

Vậy: x=12

h) Ta có: \(5\left(3x-1\right)+7\left(3x-1\right)=96\)

\(\Leftrightarrow12\left(3x-1\right)=96\)

\(\Leftrightarrow3x-1=8\)

\(\Leftrightarrow3x=9\)

hay x=3(nhận)

Vậy: x=3

Bài làm

3x - 5 = -7 - 13

=> 3x = -7 - 13 + 5

=> 3x = -15

=> x = -5

Vậy x = -5

26 tháng 2 2020

\(3x-5=-7-13\)

\(\Leftrightarrow-3x-5=-20\)

\(\Leftrightarrow-3x=-15\)

\(\Leftrightarrow x=5\)

Vậy x=5

3 tháng 2 2018

3x - 2x = 13 - 19

   x      = -6

Vậy x = -6

3x + 7   = 4 - 3x

3x + 3x = 7 - 4

 6x        = 3

   x        = 3 : 6

   x        = \(\frac{1}{2}\)

Vậy x = \(\frac{1}{2}\)

5 ( x + 1 ) -3 x   = x + 9         

5 . x + 5 . 1 - 3x = x + 9

5x + 5 - 3x         = x + 9

5x - x - 3x + 5    = 9

4x - 3x               = 9 - 5

 x                      = 4

Vậy x = 4

3 tháng 2 2018

A) 3x-2x=13-19

=>.      x=-6

   Vậy x=-6

b)3x+7=4-3x

=>3x+3x=4-7

=>.     6x=-3

=>.       x=-3/6

     Vậy x=-3/6

c)5(x+1)-3x=x+9

=>5x+5-3x=x+9

=>. 5x-3x-x=9-5

 =>.          x=4

     Vậy x=4

    Chúc bạn học tốt nhé!

19 tháng 3 2020

\(\text{3x- 5= -7- 13}\)

\(3x-5=-20\)

\(3x=-20+5\)

\(3x=-15\)

\(\Rightarrow x=-5\)

19 tháng 3 2020

3x - 5 = -7 - 13

<=> 3x = -7 - 13 + 5

<=> 3x = -15

<=> x = -5

Vậy......

a: \(=\dfrac{-3}{5}\cdot\dfrac{5}{7}+\dfrac{-3}{5}\cdot\dfrac{3}{7}+\dfrac{-3}{5}\cdot\dfrac{6}{7}\)

\(=\dfrac{-3}{5}\left(\dfrac{5}{7}+\dfrac{3}{7}+\dfrac{6}{7}\right)=\dfrac{-3}{5}\cdot2=-\dfrac{6}{5}\)

b: \(=\dfrac{3}{13}\cdot\dfrac{6}{11}+\dfrac{3}{13}\cdot\dfrac{5}{11}-\dfrac{2}{13}=\dfrac{3}{13}-\dfrac{2}{13}=\dfrac{1}{13}\)

c: =>1/2x+1+3/8=7/16

=>1/2x=-15/16

=>x=-15/8

d: =>5/2x-1/3=1/6*(-9)/2=-9/12=-3/4

=>5/2x=-3/4+1/3=-9/12+4/12=-5/12

=>x=-1/6

26 tháng 2 2023

cau b là sao bn

\(\left(2x+13\right):5=17\)

\(\Rightarrow2x+13=17.5\)

\(\Rightarrow2x+13=85\)

\(\Rightarrow2x=85-13\)

\(\Rightarrow2x=72\Rightarrow x=\frac{72}{2}=36\)

\(360:\left(11x-7\right)=90\)

\(11x-7=\frac{360}{90}\)

\(\Rightarrow11x-7=4\)

\(\Rightarrow11x=4+7=11\)

\(\Rightarrow x=\frac{11}{11}=1\)

\(30:\left(3x-7\right)=15\)

\(\Rightarrow3x-7=\frac{30}{15}=2\)

\(\Rightarrow3x=2+7=9\)

\(\Rightarrow x=\frac{9}{3}=3\)

a,\(\left(2x+13\right):5=17\)

\(2x+13=17.5\)

\(2x=72\)

\(x=72:2\)

\(x=36\)

b,\(360:\left(11x-7\right)=90\)

\(11x-7=4\)

\(11x=11\)

\(x=1\)

c,\(30:\left(3x-7\right)=15\)

\(3x-7=2\)

\(3x=9\)

\(x=3\)