(x - 1) . (x+2) = 0 (x + 7) . (x-2) = 0

`( x -1) . (x+2) = 0`

`=>` \(\left[ \begin{array}{l}x-1 = 0\\x+2 = 0\end{array} \right.\) 

`=>` \(\left[ \begin{array}{l}x=0+1\\x=0-2\end{array} \right.\) 

`=>` \(\left[ \begin{array}{l}x=1\\x=-2\end{array} \right.\) 

Vậy `x \in {1;-2}`

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`(x+7) . (x-2) = 0`

`=>` \(\left[ \begin{array}{l}x+7=0\\x-2=0\end{array} \right.\) 

`=>` \(\left[ \begin{array}{l}x=0-7\\x=0+2\end{array} \right.\) 

`=>` \(\left[ \begin{array}{l}x=-7\\x=2\end{array} \right.\) 

Vậy `x \in {-7;2}`