Question

(x+5)(x-2)=0

Answer 1

\(=>\left\{{}\begin{matrix}x+5=0\\x-2=0\end{matrix}\right.=>\left\{{}\begin{matrix}x=-5\\x=2\end{matrix}\right.\)

Answer 2

\(\left(x+5\right)\left(x-2\right)=0\Leftrightarrow\left[{}\begin{matrix}TH1:x+5=0\\TH2:x-2=0\end{matrix}\right.\)

Xét `TH1:`

\(x+5=0\\ \Rightarrow x=-5\)

Xét `TH2:`

\(x-2=0\\ \Rightarrow x=2\)

Vậy \(x\in\left\{-5;2\right\}\)