a )
\(x\left(2x-7\right)-4x+14=0\)
\(\Rightarrow x\left(2x-7\right)-2\left(2x-7\right)=0\)
\(\Rightarrow\left(x-2\right)\left(2x-7\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}x-2=0\\2x-7=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=2\\2x=7\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=2\\x=\dfrac{7}{2}\end{matrix}\right.\)
Vậy ...
b )
\(\left(2x+5\right)\left(3x-1\right)-\left(2x+5\right)=0\)
\(\Rightarrow\left(2x+5\right)\left(3x-1-1\right)=0\)
\(\Rightarrow\left(2x+5\right)\left(3x-2\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}2x+5=0\\3x-2=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}2x=-5\\3x=2\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=-\dfrac{5}{2}\\x=\dfrac{2}{3}\end{matrix}\right.\)
Vậy ...
c )
\(\left(2x-3\right)^2-6x+9=0\)
\(\Rightarrow\left(2x-3\right)^2-3\left(2x-3\right)=0\)
\(\Rightarrow\left(2x-3\right)\left(2x-3-3\right)=0\)
\(\Rightarrow\left(2x-3\right)\left(2x-6\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}2x-3=0\\2x-6=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}2x=3\\2x=6\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=\dfrac{3}{2}\\x=3\end{matrix}\right.\)
Vậy ...
\(a.x\left(2x-7\right)-4x+14=0\Rightarrow x\left(2x-7\right)-2\left(2x-7\right)=0\Rightarrow\left(x-2\right)\left(2x-7\right)=0\Rightarrow\left[{}\begin{matrix}x-2=0\\2x-7=0\end{matrix}\right.\Rightarrow}\left[{}\begin{matrix}x=2\\x=\dfrac{7}{2}\end{matrix}\right.\)Vậy \(x\in\left\{2;\dfrac{7}{2}\right\}\).
