a ) \(x^2+2x\Leftrightarrow x\left(x+2\right)\Leftrightarrow\left[{}\begin{matrix}x=0\\x=-2\end{matrix}\right.\)
b) \(x^2-3\Leftrightarrow\left(x-\sqrt{3}\right)\left(x+\sqrt{3}\right)\)
\(\Leftrightarrow\left[{}\begin{matrix}x=\sqrt{3}\\x=-\sqrt{3}\end{matrix}\right.\)
c ) \(\left(x-2\right)^2+4=0\Leftrightarrow\left(x-2\right)^2=-4\left(Loại\right)\)
d ) \(x^2-3x+2\Leftrightarrow\left[{}\begin{matrix}x-2=0\\x-1=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=2\\x=1\end{matrix}\right.\)
e ) \(x^2+6x+5\Leftrightarrow\left[{}\begin{matrix}x+1=0\\x+5=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=-1\\x=-5\end{matrix}\right.\)
