Với x >= 0 ; x khác 1
\(P=\left(\dfrac{4\sqrt{x}\left(\sqrt{x}-2\right)-8x}{x-4}\right):\left(\dfrac{\sqrt{x}+2+3\sqrt{x}-6}{\sqrt{x}-2}\right)\)
\(=\left(\dfrac{-4x-8\sqrt{x}}{x-4}\right):\left(\dfrac{4\sqrt{x}-4}{\sqrt{x}-2}\right)=\dfrac{-4\sqrt{x}\left(\sqrt{x}+2\right)\left(\sqrt{x}-2\right)}{\left(x-4\right).4\left(\sqrt{x}-1\right)}=\dfrac{\sqrt{x}}{1-\sqrt{x}}\)
b, Ta có \(P=-4\Rightarrow\dfrac{\sqrt{x}}{1-\sqrt{x}}=-4\Leftrightarrow\sqrt{x}=-4+4\sqrt{x}\Leftrightarrow3\sqrt{x}=4\Leftrightarrow x=\dfrac{16}{9}\left(tm\right)\)
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