Question

Tìm x biết :(x+3) (x-2)<0

Answer 1

\(\left(x+3\right)\left(x-2\right)< 0\Rightarrow x+3;x-2\)trái dấu

Mà \(x+3>x-2\)

\(\Rightarrow\hept{\begin{cases}x+3>0\\x-2< 0\end{cases}}\)

\(\Rightarrow-3< x< 2\)

Vậy ...

Answer 2

Để (x + 3)(x - 2) < 0

=> có 2 trường hợp 

\(\left(1\right)\hept{\begin{cases}x+3< 0\\x-2>0\end{cases}\Rightarrow\hept{\begin{cases}x< -3\\x>2\end{cases}\Rightarrow x\in O}}\)

\(\left(2\right)\hept{\begin{cases}x+3>0\\x-2< 0\end{cases}}\Rightarrow\hept{\begin{cases}x>-3\\x< 2\end{cases}\Rightarrow-3< x< 2}\)

=> x = {-2 ; -1 ; 0 ; 1 }