a: \(P=\left(\sqrt{x}-\dfrac{x+2}{\sqrt{x}+1}\right):\left(\dfrac{\sqrt{x}}{\sqrt{x}+1}-\dfrac{\sqrt{x}-4}{1-x}\right)\)
\(=\dfrac{\sqrt{x}\left(\sqrt{x}+1\right)-x-2}{\sqrt{x}+1}:\dfrac{\sqrt{x}\left(\sqrt{x}-1\right)+\sqrt{x}-4}{x-1}\)
\(=\dfrac{x+\sqrt{x}-x-2}{\sqrt{x}+1}\cdot\dfrac{x-1}{x-\sqrt{x}+\sqrt{x}-4}\)
\(=\dfrac{\sqrt{x}-1}{x-4}\cdot\left(\sqrt{x}-2\right)=\dfrac{\sqrt{x}-1}{\sqrt{x}+2}\)
b: Khi x=4/25 thì \(P=\dfrac{\dfrac{2}{5}-1}{\dfrac{2}{5}+2}=\dfrac{-3}{5}:\dfrac{12}{5}=-\dfrac{1}{4}\)
Đúng 2
Bình luận (0)
