vì x.(x+3)=0
suy ra
x=0 hoặc x+3=0
suy ra x=0 hoặc x=-3
vậy x=-3 :0
x . x + 3 trái dấu
Ta có: \(x\left(x+3\right)=x+x-3=3>0\Rightarrow\hept{\begin{cases}x>0\\x+3< 0\end{cases}}\Rightarrow\hept{\begin{cases}x>0\\x< 3\end{cases}}\)
\(\Rightarrow0< x< 3\Rightarrow x\in\left\{1;2;3\right\}\)
\(x\left(x+3\right)=0\)
\(\Rightarrow x=0\) hoac \(x+3=0\)
suy ra x=0 hoac x=-3
Vay ......