Question

2x(x+81)=0

Answer 1

\(2x\left(x+81\right)=0\\ \Rightarrow\left\{{}\begin{matrix}2x=0\\x+81=0\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}x=0\\x=-81\end{matrix}\right.\)

Answer 2

x= -81

Answer 3

\(x\in\left\{0;-81\right\}\)