\(a;\Leftrightarrow-2x< -6\Leftrightarrow x>3\)
\(b;\Leftrightarrow-4x>-8\Leftrightarrow x< 2\)
\(c;\Leftrightarrow x-2x\le7\Leftrightarrow-x\le7\Leftrightarrow x\ge-7\)
\(\sqrt{x-1}=\sqrt{3-x}\left(đk:1\le x\le3\right)\)
\(pt\Leftrightarrow x-1=3-x\Leftrightarrow x=2\left(tm\right)\)
\(a;\left(đk:x>0\right)\Rightarrow\dfrac{x+\sqrt{x}}{\sqrt{x}}+\dfrac{x-1}{\sqrt{x}+1}=\dfrac{\sqrt{x}\left(\sqrt{x}+1\right)}{\sqrt{x}}+\dfrac{\left(\sqrt{x}+1\right)\left(\sqrt{x}-1\right)}{\sqrt{x}+1}=\sqrt{x}+1+\sqrt{x}-1=2\sqrt{x}\)
\(b;\left(đk:x\ge0;x\ne4\right)\Rightarrow\dfrac{x+2\sqrt{x}}{\sqrt{x}+2}+\dfrac{x-4\sqrt{x}+4}{\sqrt{x}-2}=\dfrac{\sqrt{x}\left(\sqrt{x}+2\right)}{\sqrt{x}+2}+\dfrac{\left(\sqrt{x}-2\right)^2}{\sqrt{x}-2}=\sqrt{x}+\sqrt{x}-2=2\sqrt{x}-2\)
