Question

Tìm x biết \(-2x^2-6x=0\)

Answer 1

Làmmm

-2x²-6x=0

<=> -2x(x+3)=0

<=> x(x+3)=0

<=> \(\left[{}\begin{matrix}x=0\\x+3=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\x=-3\end{matrix}\right.\)

Kl: Vậy.........

Answer 2

\(-2x^2-6x=0\\ 2x^2-6x=0\\ 2x\left(x-3\right)=0\\ \Rightarrow\left[{}\begin{matrix}2x=0\\x-3=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=0\\x=3\end{matrix}\right.\)

Vậy \(x\in\left\{0;3\right\}\)