\(P=\left(\frac{\sqrt{x}-2}{\sqrt{x}-1}-\frac{\sqrt{x}+2}{x+2\sqrt{x}+1}\right)\cdot\frac{\left(1-x\right)^2}{2}\)
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NC
24 tháng 8 2020
Nếu đề là rút gọn G thì...
đk: \(x\ge0;x\ne1\)
Ta có:
\(G=\left(\frac{\sqrt{x}}{\sqrt{x}-1}-\frac{4\sqrt{x}}{x+\sqrt{x}+1}-\frac{2\sqrt{x}+1}{x\sqrt{x}-1}\right).\left(\sqrt{x}+\frac{2\sqrt{x}+1}{\sqrt{x}-1}\right)\)
\(G=\frac{\left(x+\sqrt{x}+1\right)\sqrt{x}-4\left(\sqrt{x}-1\right)\sqrt{x}-2\sqrt{x}-1}{\left(\sqrt{x}-1\right)\left(x+\sqrt{x}+1\right)}.\frac{\left(\sqrt{x}-1\right)\sqrt{x}+2\sqrt{x}+1}{\sqrt{x}-1}\)
\(G=\frac{x\sqrt{x}+x+\sqrt{x}-4x+4\sqrt{x}-2\sqrt{x}-1}{\left(\sqrt{x}-1\right)\left(x+\sqrt{x}+1\right)}.\frac{x-\sqrt{x}+2\sqrt{x}+1}{\sqrt{x}-1}\)
\(G=\frac{x\sqrt{x}-3x+3\sqrt{x}-1}{\left(\sqrt{x}-1\right)\left(x+\sqrt{x}+1\right)}.\frac{x+\sqrt{x}+1}{\sqrt{x}-1}\)
\(G=\frac{\left(\sqrt{x}-1\right)^3.\left(x+\sqrt{x}+1\right)}{\left(\sqrt{x}-1\right)^2.\left(x+\sqrt{x}+1\right)}=\sqrt{x}-1\)
1 tháng 6 2017
\(=\left(\frac{\sqrt{x}+2}{\left(\sqrt{x}+1\right)^2}-\frac{\sqrt{x}-2}{\sqrt{x}^2-1}\right).\frac{\sqrt{x}+1}{\sqrt{x}}\)
\(=\frac{\left(\sqrt{x}+2\right)\left(\sqrt{x}-1\right)-\left(\sqrt{x}-2\right)\left(\sqrt{x}+1\right)}{\left(\sqrt{x}+1\right)^2\left(\sqrt{x}-1\right)}.\frac{\left(\sqrt{x}+1\right)}{\sqrt{x}}\)
\(=\frac{x+\sqrt{x}-2-x+\sqrt{x}+2}{\left(\sqrt{x}+1\right)^2\left(\sqrt{x}-1\right)}.\frac{\sqrt{x}+1}{\sqrt{x}}\)
\(=\frac{2\sqrt{x}}{\left(\sqrt{x}+1\right)^2\left(\sqrt{x}-1\right)}.\frac{\sqrt{x}+1}{\sqrt{x}}\)
\(=\frac{2}{\left(\sqrt{x}+1\right)\left(\sqrt{x}-1\right)}=\frac{2}{\sqrt{x}^2-1}=\frac{2}{x-1}\)
ĐKXĐ: \(x\ge0;x\ne1;\)
\(P=\left(\frac{\sqrt{x}-2}{\sqrt{x}-1}-\frac{\sqrt{x}+2}{x+2\sqrt{x}+1}\right).\frac{\left(1-x\right)^2}{2}\)
\(=\left(\frac{\sqrt{x}-2}{\sqrt{x}-1}-\frac{\sqrt{x}+2}{\left(\sqrt{x}+1\right)^2}\right).\frac{\left(1-x\right)^2}{2}\)
\(=\frac{\left(\sqrt{x}-2\right)\left(\sqrt{x}+1\right)^2-\left(\sqrt{x}+2\right)\left(\sqrt{x}-1\right)}{\left(\sqrt{x}-1\right)\left(\sqrt{x}+1\right)^2}.\frac{1-2x+x^2}{2}\)
\(=\frac{x\sqrt{x}+2x+\sqrt{x}-2x-4\sqrt{x}-2-x+\sqrt{x}-2\sqrt{x}+2}{\left(\sqrt{x}-1\right)\left(\sqrt{x}+1\right)^1}.\frac{\left(x-1\right)^2}{2}\)
\(=\frac{x\sqrt{x}-x-4\sqrt{x}}{\left(x-1\right)\left(\sqrt{x}+1\right)}.\frac{\left(x-1\right)^2}{2}\)
\(=\frac{\sqrt{x}\left(x-\sqrt{x}-4\right)\left(x-1\right)}{2\left(\sqrt{x}+1\right)}\)
\(=\frac{\sqrt{x}\left(x-\sqrt{x}-4\right)\left(\sqrt{x}-1\right)}{2}\)
Ta có: \(P=\left(\frac{\sqrt{x}-2}{\sqrt{x}-1}-\frac{\sqrt{x}+2}{x+2\sqrt{x}+1}\right)\times\frac{\left(1-x\right)^2}{2}\)
\(P=\left(\frac{\sqrt{x}-2}{\sqrt{x}-1}-\frac{\sqrt{x}+2}{\left(\sqrt{x}+1\right)^2}\right).\frac{\left(1-x\right)^2}{2}\)
\(P=\frac{\left(\sqrt{x}-2\right)\left(\sqrt{x}+1\right)^2-\left(\sqrt{x}+2\right)\left(\sqrt{x}-1\right)}{\left(\sqrt{x}-1\right)\left(\sqrt{x}+1\right)^2}.\frac{\left(1-x\right)^2}{2}\)
\(P=\frac{x\sqrt{x}-4\sqrt{x}-x}{-\left(1-x\right)\left(\sqrt{x}+1\right)}.\frac{\left(1-x\right)^2}{2}\)
\(P=\frac{\sqrt{x}\left(x-4-\sqrt{x}\right)\left(\sqrt{x}-1\right)}{2}\)