\(.a.\)
\(2x-\left(-3\right)=7\)
\(\Rightarrow2x+3=7\)
\(\Rightarrow2x=7-3\)
\(\Rightarrow2x=4\)
\(\Rightarrow x=4:2\)
\(\Rightarrow x=2\)
Vậy \(x=2\)
\(.b.\)
\(\left(x-5\right)\left(x+6\right)=0\)
\(\Rightarrow\left[\begin{matrix}\left(x-5\right)=0\\\left(x+6\right)=0\end{matrix}\right.\)
\(\Rightarrow\left[\begin{matrix}x=0+5\\x=0-6\end{matrix}\right.\)
\(\Rightarrow\left[\begin{matrix}x=5\\x=-4\end{matrix}\right.\)
Vậy \(\left[\begin{matrix}x=5\\x=-4\end{matrix}\right.\)
