\(\left(x-2015\right)\left(x+2016\right)=0\\ \Rightarrow\left[{}\begin{matrix}x-2015=0\\x+2016=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=2015\\x=-2016\end{matrix}\right.\)
vậy ...
\(\left(x-2015\right)\left(x+2016\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x-2015=0\\x+2016=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=2015\\x=-2016\end{matrix}\right.\)
Vậy \(x\in\left\{2015;-2016\right\}\)