Question

X^2-2x>=0

Answer 1

\(x^2-2x\ge0\)

\(\Leftrightarrow x\left(x-2\right)\ge0\)

\(\Leftrightarrow\left[{}\begin{matrix}\left\{{}\begin{matrix}x\ge0\\x-2\ge0\end{matrix}\right.\\\left\{{}\begin{matrix}x\le0\\x-2\le0\end{matrix}\right.\end{matrix}\right.\)\(\Leftrightarrow\left[{}\begin{matrix}\left\{{}\begin{matrix}x\ge0\\x\ge2\end{matrix}\right.\\\left\{{}\begin{matrix}x\le0\\x\le2\end{matrix}\right.\end{matrix}\right.\)\(\Leftrightarrow\left[{}\begin{matrix}x\ge2\\x\le0\end{matrix}\right.\)

Vậy...

Answer 2

\(x^2-2x\ge0\\ \Leftrightarrow x\left(x-2\right)\ge0\\ \Leftrightarrow\left[{}\begin{matrix}x\ge0\\x-2\ge0\end{matrix}\right.\\\Leftrightarrow \left[{}\begin{matrix}x\ge0\\x\ge2\end{matrix}\right.\\ \Leftrightarrow x\ge2\)

Vậy \(x\ge2\)