\(\dfrac{x-1}{2x^2-4x}-\dfrac{7}{8x}=\dfrac{5-x}{4x^2-8x}-\dfrac{1}{8x-16}\) ( ĐKXĐ: \(x\ne0;x\ne2\) )

\(\Leftrightarrow\dfrac{x-1}{2x\left(x-2\right)}-\dfrac{7}{8x}=\dfrac{5-x}{4x\left(x-2\right)}-\dfrac{1}{8\left(x-2\right)}\)

\(\Leftrightarrow\dfrac{\left(x-1\right)4}{8x\left(x-2\right)}-\dfrac{7\left(x-2\right)}{8x\left(x-2\right)}=\dfrac{2\left(5-x\right)}{8x\left(x-2\right)}-\dfrac{1x}{8x\left(x-2\right)}\)

\(\Rightarrow4x-4-7x+14=10-2x-x\)

\(\Leftrightarrow-3x+2x+x=10+4-14\)

\(\Leftrightarrow0=0\)

          Vậy pt đã cho có nghiệm đúng với mọi x

\(\dfrac{7}{8x}+\dfrac{5-x}{4x^2-8x}=\dfrac{x-1}{2x\left(x-2\right)}+\dfrac{1}{8x-16}\)
ĐKXĐ: x ≠ 0; x ≠ 2

\(< =>\dfrac{14x-28+20-4x}{16x\left(x-2\right)}=\dfrac{8x-8+2x}{16x\left(x-2\right)}\)
Suy ra: 14x - 28 + 20 - 4x = 8x - 8 + 2x
<=> 14x - 8x - 2x - 4x = 28 - 20 - 8
<=> 0x = 0
Vậy: S = { x | x ≠ 0;2 }

a:Sửa đề: \(\dfrac{3}{5x-1}+\dfrac{2}{3-x}=\dfrac{4}{\left(1-5x\right)\left(x-3\right)}\)

=>3x-9-10x+2=-4

=>-7x-7=-4

=>-7x=3

=>x=-3/7

b: =>\(\dfrac{5-x}{4x\left(x-2\right)}+\dfrac{7}{8x}=\dfrac{x-1}{2x\left(x-2\right)}+\dfrac{1}{8\left(x-2\right)}\)

=>\(2\left(5-x\right)+7\left(x-2\right)=4\left(x-1\right)+x\)

=>10-2x+7x-14=4x-4+x

=>5x-4=5x-4

=>0x=0(luôn đúng)

Vậy: S=R\{0;2}

3x.|x+1|−2x|x+2|=12

Với x < -2 ta có: 3x.(-x-1)-2x(-x-2)-12=0

<=> -3x² - 3x + 2x² + 4x -12 =0

<=> -x² - x - 12=0

$\Leftrightarrow $ -(x² +x+12)=0 ( vô lý)

Làm tương tự với 2 trường hợp còn lại:

ĐKXĐ: x∉{0;2}

Ta có: \(\frac{5-x}{4x^2-8x}+\frac{7}{8x}=\frac{x-1}{2x\left(x-2\right)}+\frac{1}{8x-16}\)

\(\Leftrightarrow\frac{5-x}{4x\left(x-2\right)}+\frac{7}{8x}-\frac{x-1}{2x\left(x-2\right)}-\frac{1}{8\left(x-2\right)}=0\)

\(\Leftrightarrow\frac{2\left(5-x\right)}{8x\left(x-2\right)}+\frac{7\left(x-2\right)}{8x\left(x-2\right)}-\frac{4\left(x-1\right)}{8x\left(x-2\right)}-\frac{x}{8x\left(x-2\right)}=0\)

Suy ra: \(10-2x+7x-14-4x+4-x=0\)

\(\Leftrightarrow0x=0\)

Vậy: \(\left\{{}\begin{matrix}x\in R\\x\notin\left\{0;2\right\}\end{matrix}\right.\)

\(\Leftrightarrow\) \(\dfrac{7}{8x}\)+\(\dfrac{5-x}{4x\left(x-2\right)}\)= \(\dfrac{x-1}{2x\left(x-2\right)}\)+ \(\dfrac{1}{8\left(x-2\right)}\)

\(\Rightarrow\) 7(x-2) + 2(5-x) = 4(x-1) +x

\(\Leftrightarrow\) 7x-2x+10-2x= 4x-4+x

\(\Leftrightarrow\)7x-2x-2x-4x-x = -4-10

\(\Leftrightarrow\) -2x = -14

\(\Leftrightarrow\) x = 7

Vậy phương trình có nghiệm x=7

+= +

7x-2x+10-2x= 4x-4+x

7x-2x-2x-4x-x = -4-10

-2x = -14

x = 7

vậy tập của phương trình là: S=7}

a) \(\left(x^2-4\right)-\left(x-2\right)\left(3-2x\right)\)

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

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

\(=\left(x-2\right)\left(3x-1\right)\)

b) ĐKXĐ: x ≠ 5; x ≠ -5

Với điều kiện trên ta có:

\(\dfrac{x+5}{x^2-5x}-\dfrac{x-5}{2x^2+10x}=\dfrac{x+25}{2x^2-50}\)

\(\Leftrightarrow\dfrac{x+5}{x\left(x-5\right)}-\dfrac{x-5}{2x\left(x+5\right)}-\dfrac{x+25}{2\left(x^2-25\right)}=0\)

\(\Leftrightarrow\dfrac{x+5}{x\left(x-5\right)}-\dfrac{x-5}{2x\left(x+5\right)}-\dfrac{x+25}{2\left(x-5\right)\left(x+5\right)}=0\)

\(\Rightarrow2\left(x+5\right)^2-\left(x-5\right)^2-x\left(x+25\right)=0\)

\(\Leftrightarrow2x^2+20x+50-x^2+10x-25-x^2-25x=0\)

\(\Leftrightarrow5x-25=0\)

\(\Leftrightarrow5x=25\)

\(\Leftrightarrow x=5\)(Không thỏa mãn ĐKXĐ)

Vậy tập nghiệm của phương trình là S = ∅

c) ĐKXĐ: x ≠ 1

Với điều kiện trên ta có:

\(\dfrac{1}{x-1}-\dfrac{3x^2}{x^3-1}=\dfrac{2x}{x^2+x+1}\)

\(\Leftrightarrow\dfrac{1}{x-1}-\dfrac{3x^2}{\left(x-1\right)\left(x^2+x+1\right)}-\dfrac{2x}{x^2+x+1}=0\)

\(\Rightarrow x^2+x+1-3x^2-2x\left(x-1\right)=0\)

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

\(\Leftrightarrow-4x^2+3x+1=0\)

\(\Leftrightarrow-4x^2+4x-x+1=0\)

\(\Leftrightarrow-4x\left(x-1\right)-\left(x-1\right)=0\)

\(\Leftrightarrow\left(x-1\right)\left(-4x-1\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x-1=0\\-4x-1=0\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=1\left(Khôngthoảman\right)\\x=-\dfrac{1}{4}\left(Thỏamãn\right)\end{matrix}\right.\)

Vậy tập nghiệm của phương trình là \(S=\left\{-\dfrac{1}{4}\right\}\)

1.  ĐKXĐ: $x\neq 1$

Sửa lại đề 1 chút:

$\frac{1}{x-1}-\frac{3x^2}{x^3-1}=\frac{2x}{x^2+x+1}$

$\Leftrightarrow \frac{x^2+x+1}{(x-1)(x^2+x+1)}-\frac{3x^2}{(x-1)(x^2+x+1)}=\frac{2x(x-1)}{(x-1)(x^2+x+1)}$

$\Leftrightarrow x^2+x+1-3x^2=2x(x-1)$

$\Leftrightarrow 4x^2-3x-1=0$

$\Leftrightarrow (4x+1)(x-1)=0$

Vì $x\neq 1$ nên $x=-\frac{1}{4}$

2. ĐKXĐ: $x\neq 0;2$

PT \(\Leftrightarrow \frac{7}{8x}+\frac{5-x}{4x(x-2)}=\frac{x-1}{2x(x-2)}+\frac{1}{8(x-2)}\)

\(\Leftrightarrow \frac{7(x-2)}{8x(x-2)}+\frac{2(5-x)}{8x(x-2)}=\frac{4(x-1)}{8x(x-2)}+\frac{x}{8x(x-2)}\)

\(\Leftrightarrow 7(x-2)+2(5-x)=4(x-1)+x\)

\(\Leftrightarrow 5x-4=5x-4\) (luôn đúng)

Vậy pt có nghiệm $x\in\mathbb{R}$ với $x\neq 0;2$

3.

$(x^2+5x)^2-2(x^2+5x)=24$

$\Leftrightarrow (x^2+5x)^2-2(x^2+5x)+1-25=0$

$\Leftrightarrow (x^2+5x-1)^2-5^2=0$

$\Leftrightarrow (x^2+5x-6)(x^2+5x+4)=0$

$\Leftrightarrow (x-1)(x+6)(x+1)(x+4)=0$

$\Leftrightarrow x\in\left\{\pm 1;-4;-6\right\}$

ĐKXĐ : \(\left\{{}\begin{matrix}4x^2-1\ne0\\8x^3+1\ne0\end{matrix}\right.\Leftrightarrow x\ne\pm\dfrac{1}{2}\)

\(P=\dfrac{2x^5-x^4-2x+1}{4x^2-1}+\dfrac{8x^2-4x+2}{8x^3+1}\)

\(=\dfrac{\left(x^4-1\right)\left(2x-1\right)}{\left(2x-1\right)\left(2x+1\right)}+\dfrac{2\left(4x^2-2x+1\right)}{\left(2x+1\right)\left(4x^2-2x+1\right)}\)

\(=\dfrac{x^4-1}{2x+1}+\dfrac{2}{2x+1}=\dfrac{x^4+1}{2x+1}\)

https://sg.docworkspace.com/l/sIM-LioBEocfloAY