Question

giúp mình với

Answer 1

\(1,A=\dfrac{2\cdot2-1}{3-2}=3\\ 2,B=\dfrac{\sqrt{x}-x+25+2\sqrt{x}-25}{\sqrt{x}\left(\sqrt{x}+5\right)}\\ B=\dfrac{-x+3\sqrt{x}}{\sqrt{x}\left(\sqrt{x}+5\right)}=\dfrac{\sqrt{x}\left(3-\sqrt{x}\right)}{\sqrt{x}\left(\sqrt{x}+5\right)}=\dfrac{3-\sqrt{x}}{\sqrt{x}+5}\\ 3,B< 0\Leftrightarrow3-\sqrt{x}< 0\left(\sqrt{x}+5>0\right)\\ \Leftrightarrow\sqrt{x}>3\Leftrightarrow x>9\)