a)
\(\Leftrightarrow\left[{}\begin{matrix}x^2=0\\7x-3=0\end{matrix}\right.\\ \Leftrightarrow\left[{}\begin{matrix}x=0\\x=\dfrac{3}{7}\end{matrix}\right.\)
b)
\(\Leftrightarrow\left[{}\begin{matrix}2x+1=0\\-x^2-2=0\end{matrix}\right.\\ \Leftrightarrow\left[{}\begin{matrix}x=-\dfrac{1}{2}\\x^2=\dfrac{2}{-1}=-2\left(vô.lí\right)\end{matrix}\right.\)
c)
\(\Leftrightarrow\left[{}\begin{matrix}x^2+4=0\\2x-3=0\end{matrix}\right.\\ \Leftrightarrow\left[{}\begin{matrix}x^2=-4\left(vô.lí\right)\\x=\dfrac{3}{2}\end{matrix}\right.\)
d)
\(\Leftrightarrow\left[{}\begin{matrix}x+6=0\\\dfrac{x^2+3-2}{2}=0\end{matrix}\right.\\ \Leftrightarrow\left[{}\begin{matrix}x=-6\\\dfrac{x^2+1}{2}=0\left(vô.lí\right)\end{matrix}\right.\)
e)
\(\Leftrightarrow\left[{}\begin{matrix}x^2+x+1=0\\6-2x=0\end{matrix}\right.\\ \Leftrightarrow\left[{}\begin{matrix}x^2+2.\dfrac{1}{2}x+\dfrac{1}{4}+\dfrac{3}{4}=0\\2x=6\end{matrix}\right.\\ \Leftrightarrow\left[{}\begin{matrix}\left(x+\dfrac{1}{2}\right)^2+\dfrac{3}{4}=0\left(vô.lí\right)\\x=3\end{matrix}\right.\)
f)
\(\Leftrightarrow\left[{}\begin{matrix}8x-4=0\\x^2-2x+2=0\end{matrix}\right.\\ \Leftrightarrow\left[{}\begin{matrix}x=\dfrac{4}{8}=\dfrac{1}{2}\\\left(x-1\right)^2+1=0\left(vô.lý\right)\end{matrix}\right.\)
