a) \(x\left(x-2\right)\ge0\)
\(\Rightarrow x\ge0\)hoặc \(x-2\ge0\)
\(\Rightarrow x\ge0\)hoặc \(x\ge2\)
\(S=\left\{xlx\ge0\right\}\)
b)\(x\left(x-2\right)\le0\)
\(\Rightarrow x\le0\)hoặc \(x-2\le0\)
\(\Rightarrow x\le0\)hoặc \(x\le2\)
\(S=\left\{xlx\le2\right\}\)