(x-5).(x ²-4)=0 giúp mk vs nha mk ko bt làm

2 câu trả lời

(x-5).($x^{2}$ -4)=0

⇔\(\left[ \begin{array}{l}x-5=0\\x^{2} -4=0\end{array} \right.\) 

⇔\(\left[ \begin{array}{l}x=5\\x^{2} =4\end{array} \right.\) 

⇔\(\left[ \begin{array}{l}x=5\\x=±2\end{array} \right.\) .

Vậy x ∈(5;±2)

 

$(x-5)(x^2-4)=0 \\
\Leftrightarrow \left[\begin{matrix}
x-5=0 & \\ 
x^2-4=0 & 
\end{matrix}\right. \\
\Leftrightarrow \left[\begin{matrix}
x=5 & \\ 
x=2;x=-2 & 
\end{matrix}\right.$