3. (x - 1)(x - 2)(x + 1) = 0
<=> \(\left[{}\begin{matrix}x-1=0\\x-2=0\\x+1=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=1\\x=2\\x=-1\end{matrix}\right.\)
1) \(4x-3=2x+7\)
\(\Rightarrow2x=10\Rightarrow x=5\)
2) \(\left|x-2\right|=4-2x\)
\(\Rightarrow\left[{}\begin{matrix}x-2=4-2x\left(x\ge2\right)\\2-x=4-2x\left(x< 2\right)\end{matrix}\right.\)\(\Rightarrow\left[{}\begin{matrix}x=2\left(tm\right)\\x=2\left(l\right)\end{matrix}\right.\)\(\Rightarrow x=2\)
3) \(\left(x-1\right)\left(x-2\right)\left(x+1\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}x-1=0\\x-2=0\\x+1=0\end{matrix}\right.\)\(\Rightarrow\left[{}\begin{matrix}x=1\\x=2\\x=-1\end{matrix}\right.\)
4) \(\dfrac{1}{x+2}-\dfrac{5}{x-2}=\dfrac{2x-3}{x^2-4}\left(đk:x\ne2\right)\)
\(\Rightarrow\dfrac{x-2-5x-10}{x^2-4}=\dfrac{2x-3}{x^2-4}\)
\(\Rightarrow-4x-12=2x-3\)
\(\Rightarrow6x=-9\Rightarrow x=-\dfrac{3}{2}\)(thỏa đk)