\(a,\Rightarrow4x^2-20x-4x^2+3x+4x-3=5\\ \Rightarrow-13x=8\Rightarrow x=-\dfrac{8}{13}\\ b,\Rightarrow3x^2-10x+8-3x^2+27x=-3\\ \Rightarrow17x=-11\Rightarrow x=-\dfrac{11}{17}\\ c,\Rightarrow\left(x+3\right)\left(2-x\right)=0\Rightarrow\left[{}\begin{matrix}x=-3\\x=2\end{matrix}\right.\\ d,\Rightarrow2x\left(4x^2-25\right)=0\\ \Rightarrow2x\left(2x-5\right)\left(2x+5\right)=0\Rightarrow\left[{}\begin{matrix}x=0\\x=\dfrac{2}{5}\\x=-\dfrac{2}{5}\end{matrix}\right.\\ e,Sửa:\left(4x-3\right)^2-3x\left(3-4x\right)=0\\ \Rightarrow\left(4x-3\right)^2+3x\left(4x-3\right)=0\\ \Rightarrow\left(4x-3\right)\left(7x-3\right)=0\Rightarrow\left[{}\begin{matrix}x=\dfrac{3}{4}\\x=\dfrac{3}{7}\end{matrix}\right.\)

a.

4x(x-5) - (x-1)(4x-3)-5=0

 4x^2-20x-4x^2+3x+4x+3=0

(4x^2-4x^2)+(-20x+3x+4x)+3=0

 13x+3 = 0

13x=-3

x=-3/13

b,

(3x-4)(x-2)-3x(x-9)+3=0

3x^2-6x-4x+8 - 3x^2+27x+3=0

(3x^2-3x^2)+(-6x-4x+27x)+(8+3)=0

17x+11=0

17x=-11

x=-11/17

c, 2(x+3)-x^2-3x=0

2(x+3) - x(x+3)=0

(x+3)(2-x)=0

TH1: x+3 = 0; x=-3

TH2: 2-x=0;x=2

mk giải ở dưới được 2 câu rùi nhưng ko chắc cau 2 ~~~

5465765756876

1,1/3+1/2:X= -4

         1/2:X= -4-1/3

         1/2:X= -13/3

              X=1/2 : -13/3

             X= -3/26

Giúp với

1. 1/3 + 1/2 : x = -4

   => 1/2 : x = -4 - 1/3

        1/2 : x = -13/3

      => x = 1/2 : (-13/3)

          x = -3/26

2. 3x - 30%.x = -5,4

     3x - x = -18

      2x = -18

=> x = -18 : 2

     x = -9

3. x-43 = (57 - x) - 50

  => (57 - x) . (x - 43) = -50

=> 57 - x = -50 => x = 107

=> x - 43 = -50 => x = -50 + 43 = -7

4. 3/8 - 1/6x = 1/4

 => 1/6x = 3/8 - 1/4 = 1/8

=> x = 1/8 : 1/6 = 3/4

5. 2/3 + 1/3 : x = 3/5

=> 1/3 : x = 3/5 - 2/3 = -1/15

=> x = 1/3 : (-1/15) = -5

6. x + 30%x = -1/3

 bó tay hihi!!!!

a) Ta có: \(6x\left(x-5\right)+3x\left(7-2x\right)=18\)

\(\Leftrightarrow6x^2-30x+21x-6x^2=18\)

\(\Leftrightarrow-9x=18\)

hay x=-2

Vậy: S={-2}

b) Ta có: \(2x\left(3x+1\right)+\left(4-2x\right)\cdot3x=7\)

\(\Leftrightarrow6x^2+2x+12x-6x^2=7\)

\(\Leftrightarrow14x=7\)

hay \(x=\dfrac{1}{2}\)

Vậy: \(S=\left\{\dfrac{1}{2}\right\}\)

c) Ta có: \(0.5x\left(0.4-4x\right)+\left(2x+5\right)\cdot x=-6.5\)

\(\Leftrightarrow0.2x-2x^2+2x^2+5x=-6.5\)

\(\Leftrightarrow5.2x=-6.5\)

hay \(x=-\dfrac{5}{4}\)

Vậy: \(S=\left\{-\dfrac{5}{4}\right\}\)

d) Ta có: \(\left(x+3\right)\left(x+2\right)-\left(x-2\right)\left(x+5\right)=6\)

\(\Leftrightarrow x^2+5x+6-\left(x^2+3x-10\right)=6\)

\(\Leftrightarrow x^2+5x+6-x^2-3x+10=6\)

\(\Leftrightarrow2x+16=6\)

\(\Leftrightarrow2x=-10\)

hay x=-5

Vậy: S={-5}

e) Ta có: \(3\left(2x-1\right)\left(3x-1\right)-\left(2x-3\right)\left(9x-1\right)=0\)

\(\Leftrightarrow3\left(6x^2-5x+1\right)-\left(18x^2-29x+3\right)=0\)

\(\Leftrightarrow18x^2-15x+3-18x^2+29x-3=0\)

\(\Leftrightarrow14x=0\)

hay x=0

Vậy: S={0}

`a)5/8x+2/5=1/5`

`=>5/8x=1/5-2/5`

`=>5/8x=-1/5`

`=>x=-1/5:5/8=-8/25`

`b)5/7:x+11/7=18/7`

`=>5/7:x=18/7-11/7`

`=>5/7:x=1`

`=>x=5/7`

`c)(-1,2).(-3/24)+(0,4-1 4/15):1 2/3`

`=(-6/5).(-1/8)+(2/5-19/15):5/3`

`=3/20+(-13/15)*3/5`

`=3/20-13/25=-37/100`

a)5/8.x+2/5=1/5

5/8.x=1/5 - 2/5

5/8.x=-1/5

x=(-1/5):5/8

x=(-1/5).8/5

x=-8/25.      Vậy x=-8/25

b)5/7:x +11/7=18/7

5/7:x=1

x=5/7:1

x=5/7.      Vậy x=5/7

a) Ta có: \(\dfrac{5}{8}x+\dfrac{2}{5}=\dfrac{1}{5}\)

\(\Leftrightarrow x\cdot\dfrac{5}{8}=\dfrac{-1}{5}\)

\(\Leftrightarrow x=\dfrac{-1}{5}:\dfrac{5}{8}=\dfrac{-1}{5}\cdot\dfrac{8}{5}=\dfrac{-8}{25}\)

b) Ta có: \(\dfrac{5}{7}:x+\dfrac{11}{7}=\dfrac{18}{7}\)

\(\Leftrightarrow\dfrac{5}{7}:x=1\)

hay \(x=\dfrac{5}{7}\)

B. 7