a: \(\Leftrightarrow x\cdot\dfrac{3}{5}=\dfrac{-1}{7}+\dfrac{1}{2}=\dfrac{1}{2}-\dfrac{1}{7}=\dfrac{5}{14}\)

\(\Leftrightarrow x=\dfrac{5}{14}:\dfrac{3}{5}=\dfrac{25}{42}\)

b: =>|3x-1|=2

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

c: \(\Leftrightarrow7\left(37-x\right)=3\left(x-13\right)\)

=>259-7x=3x-39

=>-10x=-298

hay x=29,8

d: =>x=3/4+2/3=9/12+8/12=17/12

\(\frac{7}{8}\cdot\left(\frac{4}{7}-1\frac{1}{7}x\right)=0,75-3x\)

\(\Rightarrow\frac{1}{2}-x=0,75-3x\)

\(\Rightarrow-4x=0,75-\frac{1}{2}\)

\(\Rightarrow-4x=0,25\)

\(\Rightarrow x=0,25:\left(-4\right)=-0,0625\)

a,3x-0,75=-1,2

3x=-1,2+-0,75

3x=-9/20

x=-9/20:3

x=-3/20

kl:....

b,2/3/5:(2x-1/2)=1,3

2/3/5??????

c,3/4x-5/6=7/12x-5/4

3/4x-7/12x=-5/4+5/6

9/12x-7/12x=-15/12+10/12

2/12x=-5/12

2:12x=-5/12

12x=2:-5/12

12x=-24/5

x=-24/5:12

x=-2/5

kl:....

chúc bn học tốt

\(\dfrac{1}{2}-\left|2-3x\right|=\sqrt{\dfrac{19}{16}}-\sqrt{\left(-0,75\right)^2}\\ \Rightarrow\dfrac{1}{2}-\left|2-3x\right|=\dfrac{\sqrt{19}}{4}-\dfrac{3}{4}\\ \Rightarrow\left|2-3x\right|=\dfrac{1}{2}-\dfrac{\sqrt{19}-3}{4}\)

\(\Rightarrow\left|2-3x\right|=\dfrac{5-\sqrt{19}}{4}\)

\(TH_1:x\le\dfrac{2}{3}\\ 2-3x=\dfrac{5-\sqrt{19}}{4}\\ \Rightarrow3x=\dfrac{3+\sqrt{19}}{4}\\ \Rightarrow x=\dfrac{3+\sqrt{19}}{12}\left(tm\right)\)

\(TH_2:x>\dfrac{2}{3}\\ 3x-2=\dfrac{5-\sqrt{19}}{4}\\ \Rightarrow3x=\dfrac{13-\sqrt{19}}{4}\\ \Rightarrow x=\dfrac{13-\sqrt{19}}{12}\left(tm\right)\)

Vậy \(x\in\left\{\dfrac{3+\sqrt{19}}{12};\dfrac{13-\sqrt{19}}{12}\right\}\)

\(\dfrac{1}{2}-\left|2-3x\right|=\sqrt[]{\dfrac{19}{16}}-\sqrt[]{\left(-0,75\right)^2}\)

\(\Rightarrow\dfrac{1}{2}-\left|2-3x\right|=\dfrac{\sqrt[]{19}}{4}-0,75\)

\(\Rightarrow\dfrac{1}{2}-\left|2-3x\right|=\dfrac{\sqrt[]{19}}{4}-\dfrac{3}{4}\)

\(\Rightarrow\left|2-3x\right|=\dfrac{1}{2}-\dfrac{\sqrt[]{19}}{4}+\dfrac{3}{4}\)

\(\Rightarrow\left|2-3x\right|=\dfrac{5-\sqrt[]{19}}{4}\)

\(\Rightarrow\left[{}\begin{matrix}2-3x=\dfrac{5-\sqrt[]{19}}{4}\\2-3x=\dfrac{-5+\sqrt[]{19}}{4}\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}3x=2-\dfrac{5-\sqrt[]{19}}{4}\\3x=2-\dfrac{\sqrt[]{19}-5}{4}\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}3x=\dfrac{3+\sqrt[]{19}}{4}\\3x=\dfrac{13-\sqrt[]{19}}{4}\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=\dfrac{3+\sqrt[]{19}}{12}\\x=\dfrac{13-\sqrt[]{19}}{12}\end{matrix}\right.\)

bạn viết giá trị tuyệt đối bàng cách nào vậy ?

kb đi rồi nói cho nghe bạn Phạm Hoàng Phát...

bài này sai đầu bài rồi bạn ơi

-3,5 nha

x : 2 + 6 + x = 0,75

x * \(\frac{1}{2}\)+ 6 + x = 0,75

x * \(\left(\frac{1}{2}+1\right)\)+ 6 = 0,75

x *\(\frac{3}{2}\)= 0,75 - 6

x *\(\frac{3}{2}\)= -5,25

x = -5,25 : \(\frac{3}{2}\)

x = -3,5

Đ/S : 3,5

k mk nha !

bạn làm đúng rồi nhé

chúc bạn học tốt@

CÂU 10:

a, -x - 84 + 214 = -16                                                b, 2x -15 = 40 - ( 3x +10 )

       x                = - ( -16 -214 + 84 )                            2x + 3x = 40 -10 +15

       x                = 16 + 214 - 84                                        5x    = 45

      x                 = 146                                                        x     = 9

c, \(|-x-2|-5=3\)                                                             d, ( x - 2)(2x + 1) = 0

    \(|-x-2|=8\)                                                                     =>  x - 2 = 0 hoặc 2x + 1 = 0

    => - x - 2 = 8 hoặc x + 2 = 8                                                                         \(\orbr{\begin{cases}x-2=0\\2x+1=0\end{cases}=>}\orbr{\begin{cases}x=2\\x=-\frac{1}{2}\end{cases}}\)

\(\orbr{\begin{cases}-x-2=8\\x+2=8\end{cases}=>\orbr{\begin{cases}x=-10\\x=6\end{cases}}}\)

CÂU 11:

Ta có : VT = - ( - a + b + c ) + ( b + c -1 ) = a - b - c + b + c - 1 = a - 1

           VP = ( b - c + 6 ) - ( 7 - a + b ) + c = b - c + 6 - 7 + a - b + c = a - 1

=> VT = VP hay - ( -a + b +c ) + ( b + c -1 ) = ( b - c + 6 ) - ( 7 - a + b ) + c 

1) 2,75 - 5/6 × 2/5 = 2,75 - (5/6) × (2/5) = 2,75 - 1/3 = 2,75 - 0,33 = 2,42

2) 1,25 - (5/6 - 0,75) - 3/5 = 1,25 - (5/6 - 0,75) - 3/5 = 1,25 - (5/6 - 3/4) - 3/5 = 1,25 - (5/6 - 9/12) - 3/5 = 1,25 - (10/12 - 9/12) - 3/5 = 1,25 - 1/12 - 3/5 = 1,25 - 0,08 - 0,6 = 1,25 - 0,68 = 0,57

3) 4/9 × 0,75 + 8/5 + 3,125 = (4/9) × 0,75 + 8/5 + 3,125 = 0,44 + 8/5 + 3,125 = 0,44 + 1,6 + 3,125 = 0,44 + 4,725 = 5,165

4) 1,125 - 4/7 - 0,12 = 1,125 - (4/7) - 0,12 = 1,125 - 0,57 - 0,12 = 0,435 - 0,12 = 0,315

5) (1/3 + 0,4) × 3,5 + (1/6 + 0,75) × 6/5