Đề có sai sót chỗ nào k v bạn

a) / x + 4 / - 2/ x - 1/ = 5x ( 1 )

Lập bảng xét dấu :

* Với : x < - 4 , ta có :

( 1 ) ⇔ - x - 4 + 2( x - 1) = 5x

⇔ x - 6 = 5x

⇔ 4x = - 6

⇔ x = \(\dfrac{-3}{2}\) ( không thỏa mãn )

* Với : - 4 ≤ x < 1 , ta có :

( 1 ) ⇔ x + 4 + 2x - 2 = 5x

⇔ 3x + 2 = 5x

⇔ 2x = 2

⇔ x = 1 ( không thỏa mãn )

* Với : x ≥ 1 , ta có :

( 1) ⇔ x + 4 - 2x + 2 = 5x

⇔ 6 - x = 5x

⇔ 6x = 6

⇔ x = 1 ( TM )

KL.....

2( x - 1 ) - 5 = 3( 5 - 3x)

2x - 2 - 5 = 15 - 9x

2x - 7 = 15 - 9x

2x + 9x = 15 + 7

11x = 22

x = 2

Vậy x = 2 

\(2\left(x-1\right)-5=3\left(5-3x\right)\)

\(\Leftrightarrow2x-2-5=15-9x\)

\(\Leftrightarrow2x-\left(2+5\right)=15-9x\)

\(\Leftrightarrow2x-7=15-9x\)

\(\Leftrightarrow2x+9x=15+7\)

\(\Leftrightarrow11x=22\)

\(\Leftrightarrow x=22\div11\)

\(\Leftrightarrow x=2\)

\(\text{Vậy }x=2\)

2( x - 1 ) - 5 = 3( 5 - 3x)

    2x - 2 - 5 = 15 - 9x

         2x - 7 = 15 - 9x

      2x + 9x = 15 + 7

            11x = 22

                x = 2

- Ta có: \(\left(x^2-1\right).\left(x+2\right).\left(x-3\right)=\left(x-1\right).\left(x^2-4\right).\left(x+5\right)\)

      \(\Leftrightarrow\left(x-1\right).\left(x+1\right).\left(x+2\right).\left(x-3\right)=\left(x-1\right).\left(x-2\right).\left(x+2\right).\left(x+5\right)\)

      \(\Leftrightarrow\left(x-1\right).\left(x+1\right).\left(x+2\right).\left(x-3\right)-\left(x-1\right).\left(x-2\right).\left(x+2\right).\left(x+5\right)=0\)

      \(\Leftrightarrow\left(x-1\right).\left(x+2\right).\left[\left(x+1\right).\left(x-3\right)-\left(x-2\right).\left(x+5\right)\right]=0\)

      \(\Leftrightarrow\left(x-1\right).\left(x+2\right).\left[\left(x^2-2x-3\right)-\left(x^2+3x-10\right)\right]=0\)

      \(\Leftrightarrow\left(x-1\right).\left(x+2\right).\left(x^2-2x-3-x^2-3x+10\right)=0\)

      \(\Leftrightarrow\left(x-1\right).\left(x+2\right).\left(-5x+7\right)=0\)

+ \(x-1=0\)\(\Leftrightarrow\)\(x=1\left(TM\right)\)

+ \(x+2=0\)\(\Leftrightarrow\)\(x=-2\left(TM\right)\)

+ \(-5x+7=0\)\(\Leftrightarrow\)\(-5x=-7\)\(\Leftrightarrow\)\(x=\frac{7}{5}\left(TM\right)\)

Vậy \(S=\left\{-2,1,\frac{7}{5}\right\}\)

\(3\left(x-2\right)+4=5x-2\left(x-1\right)\\ \Leftrightarrow3x-6+4=5x-2x+2\\ \Leftrightarrow0x=4\left(vôlý\right)\)

Vậy pt vô nghiệm

\(2\left(x-2\right)-3\left(1-2x\right)=5\\ \Leftrightarrow2x-4-3+6x=5\\ \Leftrightarrow8x=12\\ \Leftrightarrow x=\dfrac{3}{2}\)

a, Đặt \(x^2=t\left(t\ge0\right)\)

Khi đó \(PT< =>t^1+4t-5=0\)

\(< =>t^2-1+4t-4=0\)

\(< =>\left(t-1\right)\left(t+1\right)+4\left(t-1\right)=0\)

\(< =>\left(t-1\right)\left(t+5\right)=0\)

\(< =>\orbr{\begin{cases}t=1\left(tm\right)\\t=-5\left(loai\right)\end{cases}}\)

\(< =>x^2=1< =>\orbr{\begin{cases}x=-1\\x=1\end{cases}}\)

Vậy ...

Thay m = 2 vào , ta có :

\(PT< =>x^2-2\left(2+1\right)x+2^2+3.2-4=0\)

\(< =>x^2-6x+6=0\)

\(< =>\left(x^2-6x+9\right)-\sqrt{3}^2=0\)

\(< =>\left(x-3-\sqrt{3}\right)\left(x-3+\sqrt{3}\right)=0\)

\(< =>\orbr{\begin{cases}x=3+\sqrt{3}\\x=3-\sqrt{3}\end{cases}}\)