\(\dfrac{3x}{2x-4}-\dfrac{1}{x}=\dfrac{2}{x^2-2x}\left(đk:x\ne0;x\ne2\right)\)

\(\Leftrightarrow\dfrac{3x^2}{2x\left(x-2\right)}-\dfrac{2\left(x-2\right)}{2x\left(x-2\right)}=\dfrac{4}{2x\left(x-2\right)}\)

\(\Leftrightarrow3x^2-2x+4=4\)

\(\Leftrightarrow3x^2-2x=0\)

\(\Leftrightarrow x\left(3x-2\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=0\\3x-2=0\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=0\left(loại\right)\\x=\dfrac{2}{3}\left(nhận\right)\end{matrix}\right.\)

Vậy nghiệm của PT là \(S=\left\{\dfrac{2}{3}\right\}\)

Với \(x\ne0,x\ne2\)

<=>\(\dfrac{3x}{2\left(x-2\right)}-\dfrac{1}{x}=\dfrac{2}{x\left(x-2\right)}\)

<=>\(\dfrac{3x^2-\left(2\left(x-2\right)\right)}{2x\left(x-2\right)}=\dfrac{4}{2x\left(x-2\right)}\)

<=>\(3x^2-2x+4=4\)

<=>\(3x^2-2x=0\)

<=>\(x\left(3x-2\right)=0\)

<=>\(\left[{}\begin{matrix}x=0\\x=\dfrac{2}{3}\end{matrix}\right.\)

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

ĐKXĐ: `x ne 2; x ne 0` 

`(1) <=> 3x/[2(x-2)] - 1/x = 2/[x(x-2)]`

`<=> (3x^2)/[2x(x-2)] - [1.2(x-2)]/[2x(x-2)] = (2.2)/[2x(x-2)]`

`<=> (3x^2 - 2x +4)/[2x(x-2)] = 4/[2x(x-2)]`

`=> 3x^2 - 2x + 4= 4`

`<=> 3x^2 - 2x = 0`

`<=> x(3x -2) =0`

`<=>`\(\left[ \begin{array}{l}x=0\\3x-2=0\end{array} \right.\) 

`<=>` \(\left[ \begin{array}{l}x=0\\x= \dfrac{2}{3}\end{array} \right.\)

Loại trường hợp `x= 0` vì không thỏa mãn ĐKXĐ

Vậy tập nghiệm của phương trình là `S= { 2/3}`

Đặt \(x^2-2x+2=t\)

\(\Rightarrow x^2-2x+3=t+1\)

\(\Rightarrow x^2-2x+4=t+2\)

\(pt\Leftrightarrow \frac{1}{t}+\frac{2}{t+1}=\frac{6}{t+2}\)

\(\Rightarrow (t+1)(t+2)+2t(t+2)=6t(t+1)\)

\(\Leftrightarrow t^2+3t+2+2t^2+4t=6t^2+6t\)

\(\Leftrightarrow 3t^2-t-2=0\)

TH1\( : t=1\)

\(\Rightarrow x^2-2x+2=1\)

\(\Leftrightarrow x=1\)

TH2:\(t=\frac{-2}{3}\) (loại)

Vậy \(x=1\)

ĐKXĐ: ` x ne 1 ; x ne 4`

`(2x+1)/(x^2-5x+4) + 5/(x-1) = 2/(x-4)`

`<=> (2x+1)/[(x-1)(x-4)] + [5(x-4)]/[(x-1)(x-4)] = [2(x-1)]/[(x-1)(x-4)]`

`=> 2x+1 + 5x -20 = 2x-2`

`<=> 5x = 17`

`<=> x= 17/5`(thỏa mãn ĐKXĐ)

Vậy tập nghiệm của phương trình là `S={ 17/5}`

`(3x-1)/(x-1)-(2x+5)/(x+3)+4/(x^2+2x-3)=1(x ne 1,-3)`

`<=>((3x-1)(x+3))/(x^2+2x-3)-((2x+5)(x-1))/(x^2+2x-3)+4/(x^2+2x-3)=(x^2+2x-3)/(x^2+2x-3)`

`<=>(3x-1)(x+3)-(2x+5)(x-1)+4=x^2+2x-3`

`<=>3x^2+8x-3-2x^2-3x+5+4=x^2+2x-3`

`<=>x^2+5x+6=x^2+2x-3`

`<=>3x=-9`

`<=>x=-3(loại)`

Vậy `S={cancel0}`

ĐKXĐ: \(x\notin\left\{1;-3\right\}\)

Ta có: \(\dfrac{3x-1}{x-1}-\dfrac{2x+5}{x+3}+\dfrac{4}{x^2+2x-3}=1\)

\(\Leftrightarrow\dfrac{\left(3x-1\right)\left(x+3\right)}{\left(x-1\right)\left(x+3\right)}-\dfrac{\left(2x+5\right)\left(x-1\right)}{\left(x+3\right)\left(x-1\right)}+\dfrac{4}{\left(x+3\right)\left(x-1\right)}=\dfrac{x^2+2x-3}{\left(x+3\right)\left(x-1\right)}\)

\(\Leftrightarrow\dfrac{3x^2+9x-x-3-\left(2x^2-2x+5x-5\right)+4}{\left(x+3\right)\left(x-1\right)}=\dfrac{x^2+2x-3}{\left(x+3\right)\left(x-1\right)}\)

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

\(\Leftrightarrow\dfrac{3x^2+8x+1-2x^2-3x+5}{\left(x+3\right)\left(x-1\right)}=\dfrac{x^2+2x-3}{\left(x+3\right)\left(x-1\right)}\)

Suy ra: \(x^2+5x+6-x^2-2x+3=0\)

\(\Leftrightarrow3x+9=0\)

\(\Leftrightarrow3x=-9\)

hay x=-3(Không nhận)

Vậy: \(S=\varnothing\)

b) Đặt \(x^2+2x+3=a\)(a>0)

Ta có: \(\dfrac{x^2+2x+7}{\left(x+1\right)^2+2}=x^2+2x+4\)

\(\Leftrightarrow\dfrac{x^2+2x+7}{x^2+2x+1+2}=x^2+2x+4\)

\(\Leftrightarrow\dfrac{x^2+2x+7}{x^2+2x+3}=x^2+2x+4\)

\(\Leftrightarrow\dfrac{a+4}{a}=a+1\)

\(\Leftrightarrow a^2+a=a+4\)

\(\Leftrightarrow a^2=4\)

\(\Leftrightarrow\left[{}\begin{matrix}a=2\left(nhận\right)\\a=-2\left(loại\right)\end{matrix}\right.\)

\(\Leftrightarrow x^2+2x+3=2\)

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

\(\Leftrightarrow\left(x+1\right)^2=0\)

\(\Leftrightarrow x+1=0\)

hay x=-1

Vậy: S={-1}

ĐKXĐ của cả 2 pt trên đều là `x in RR`

`a,1/(x^2-2x+2)+2/(x^2-2x+3)=6/(x^2-2x+4)`

Đặt `a=x^+2x+3(a>=2)` ta có:

`1/(a-1)+2/a=6/(a+1)`

`<=>a(a+1)+2(a-1)(a+1)=6a(a-1)`

`<=>a^2+a+2(a^2-1)=6a^2-6a`

`<=>a^2+a+2a^2-2=6a^2-6a`

`<=>3a^2-5a+2=0`

`<=>3a^2-3a-2a+2=0`

`<=>3a(a-1)-2(a-1)=0`

`<=>(a-1)(3a-2)=0`

`a>=2=>a-1>=1>0`

`a>=2=>3a-2>=4>0`

Vậy pt vô nghiệm

`(x^2+2x+7)/((x+1)^2+2)=x^2+2x+4`

`<=>(x^2+2x+7)=(x^2+2x+4)(x^2+2x+3)`

Đặt `a=x^2+2x+3(a>=2)`

`pt<=>a+4=a(a+1)`

`<=>a^2+a=a+4`

`<=>a^2=4`

`<=>a=2` do `a>=2`

`<=>(x+1)^2+2=2`

`<=>(x+1)^2=0`

`<=>x=-1`

Vậy `S={-1}`

\(\dfrac{4}{x+2}-\dfrac{1}{x}=\dfrac{x^2-2}{x^2+2x}\left(x\ne0;x\ne-2\right)\)

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

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

\(\Rightarrow4x-\left(x+2\right)=x^2-2\)

\(\Leftrightarrow4x-x-x^2=2-2\)

\(\Leftrightarrow3x-x^2=0\)

\(\Leftrightarrow x\left(3-x\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=0\left(l\right)\\x=3\left(tm\right)\end{matrix}\right.\)

\(\Leftrightarrow2x-1-\dfrac{x+2}{6}-\dfrac{x-1}{4}=0\)

\(\Leftrightarrow\dfrac{12\left(2x-1\right)-2\left(x+2\right)-3\left(x-1\right)}{12}=0\)

\(\Leftrightarrow24x-12-2x-4-3x+3=0\)

\(\Leftrightarrow19x-13=0\)

\(\Leftrightarrow x=\dfrac{13}{19}\)

a: =>(x-2)(2x+5)=0

=>x-2=0 hoặc 2x+5=0

=>x=2 hoặc x=-5/2

c: \(\dfrac{2x}{x-1}-\dfrac{x}{x+1}=1\)

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

=>x^2+3x=x^2-1

=>3x=-1

=>x=-1/3

\(a,\Leftrightarrow\left(x-2\right)\left(2x+5\right)=0\\ \Leftrightarrow\left\{{}\begin{matrix}x-2=0\\2x+5=0\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}x=2\\x=\dfrac{5}{2}\end{matrix}\right.\)

Vậy phương trình có tập nghiệm S = \(\left\{2;\dfrac{5}{2}\right\}\)

\(c,\Leftrightarrow2x.\left(x+1\right)-x.\left(x-1\right)=\left(x-1\right)\left(x+1\right)\)              ( ĐKXĐ: \(x\ne-1;x\ne1\) )

\(\Leftrightarrow2x^2+2x-x^2+x=x^2-1\\ \Leftrightarrow x^2-x^2+3x=-1\\ \Leftrightarrow3x=-1\\ \Leftrightarrow x=-\dfrac{1}{3}\)  ( nhận )

Vậy phương trình có tập nghiệm S = \(\left\{-\dfrac{1}{3}\right\}\)