Bài 1
$a)\sqrt{2x}\ge\sqrt{x}\\\Leftrightarrow \left\{\begin{matrix}x\ge0\\2x\ge x\end{matrix}\right.\Leftrightarrow x\ge0$
$b)\sqrt{2x}\le\sqrt{x^2}\\\Leftrightarrow \left\{\begin{matrix}x\ge0\\2x\le x^2\end{matrix}\right.\\\Leftrightarrow\left\{\begin{matrix}x\ge0\\\left[\begin{matrix}x\le0\\x\ge2\end{matrix}\right.\end{matrix}\right.\\\Leftrightarrow \left[\begin{matrix}x=0\\x\ge2\end{matrix}\right.$
Bài 2
a) $\sqrt{2}>1\Rightarrow \sqrt{2}+1>2$
b)$\sqrt{11}<4\Rightarrow 3\sqrt{11}<12$
c)$1<\sqrt{3}<2\Rightarrow 0<\sqrt{3}-1<1$
d)$\sqrt{3}>1;\sqrt{5}>2\Rightarrow 2-\sqrt{5}<0\\\Rightarrow \sqrt{3}>2-\sqrt{5}$
e)$\sqrt{23}<5\Rightarrow -2\sqrt{23}>-10$
f)$\sqrt{29}>5\Rightarrow -3\sqrt{29}<-15$
