Câu 1:
\(a,\sqrt{9}=\pm3\\ b,ĐK:-2x-5\ge0\Leftrightarrow x\le-\dfrac{5}{2}\\ \Leftrightarrow x\in\left\{-3;-5\right\}\\ b,\dfrac{A}{\sqrt{B}}=\dfrac{\sqrt{AB}}{B}\\ \dfrac{2}{\sqrt{3}}=\dfrac{2\sqrt{3}}{3}\\ d,C=\sqrt{3}-3\sqrt{3}+4\sqrt{3}=2\sqrt{3}\\ D=\left|\sqrt{5}-3\right|+\sqrt{5}=3-\sqrt{5}+\sqrt{5}=3\)
Câu 2:
\(a,ĐK:x\ge0;x\ne1\\ b,P=\dfrac{x-\sqrt{x}+2\sqrt{x}+2-x+2\sqrt{x}-5}{\left(\sqrt{x}-1\right)\left(\sqrt{x}+1\right)}\\ P=\dfrac{3\sqrt{x}-3}{\left(\sqrt{x}-1\right)\left(\sqrt{x}+1\right)}=\dfrac{3}{\sqrt{x}+1}\\ c,P\in Z\Leftrightarrow\sqrt{x}+1\inƯ\left(3\right)=\left\{1;3\right\}\left(\sqrt{x}+1\ge1\right)\\ \Leftrightarrow x\in\left\{0;4\right\}\left(tm\right)\)
