a. ĐKXĐ: \(\left\{{}\begin{matrix}x\ge0\\x\ne1\\x\ne4\end{matrix}\right.\)

\(A=\frac{\sqrt{x}+1-\sqrt{x}+1}{\left(\sqrt{x}-1\right)\left(\sqrt{x}+1\right)}:\frac{\left(\sqrt{x}+1\right)\left(\sqrt{x}-1\right)-\left(\sqrt{x}+2\right)\left(\sqrt{x}-2\right)}{\left(\sqrt{x}-2\right)\left(\sqrt{x}-1\right)}\)

\(=\frac{2}{\left(\sqrt{x}-1\right)\left(\sqrt{x}+1\right)}.\frac{\left(\sqrt{x}-2\right)\left(\sqrt{x}-1\right)}{3}=\frac{2\sqrt{x}-4}{3\sqrt{x}+3}\)

b. \(A< 0\Leftrightarrow\frac{2\sqrt{x}-4}{3\sqrt{x}+3}< 0\Leftrightarrow2\sqrt{x}-4< 0\Leftrightarrow x< 4\)\(\Rightarrow\left\{{}\begin{matrix}0\le x< 4\\x\ne1\end{matrix}\right.\)thì \(A< 0\)

@Võ Hồng Phúc vô giải

x + 50 = 10 x 10

x + 50 = 100

x = 100 - 50

x = 50

@Nguyễn Việt Lâm @Lê Thị Thục Hiền @Akai Haruma @Trần Thanh Phương

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