`a)` `\sqrt{2x-1}\geq \sqrt{x+1}`
`->2x-1\geqx+1`
`->2x-x\geq1+1`
`->x\geq2`
`b)``\sqrt{2x}\leq \sqrt{x^{2}}`
`->2x \leq x^{2}`
`->2x-x^{2}\leq0`
`->x.(2-x)\leq0`
`TH1:`
`->`\(\left[ \begin{array}{l}x\geq0\\2-x\leq0\end{array} \right.\) `
->`\(\left[ \begin{array}{l}x\geq0\\x\geq2\end{array} \right.\) `TH2:`
`->`\(\left[ \begin{array}{l}x\leq0\\2-x\geq0\end{array} \right.\) `
->`\(\left[ \begin{array}{l}x\leq0\\x\leq2\end{array} \right.\)