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PN
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KA
30 tháng 7 2020 lúc 19:02

Trả lời:

\(P=\left(\frac{x-\sqrt{x}+2}{x-\sqrt{x}-2}-\frac{x}{x-2\sqrt{x}}\right)\div\frac{1-\sqrt{x}}{2-\sqrt{x}}\left(ĐK:x>0,x\ne1,x\ne4\right)\)

\(P=\left[\frac{x-\sqrt{x}+2}{\left(\sqrt{x}-2\right).\left(\sqrt{x}+1\right)}-\frac{x}{\sqrt{x}.\left(\sqrt{x}-2\right)}\right]\div\frac{-\left(\sqrt{x}-1\right)}{-\left(\sqrt{x}-2\right)}\)

\(P=\left[\frac{x-\sqrt{x}+2}{\left(\sqrt{x}-2\right).\left(\sqrt{x}+1\right)}-\frac{\sqrt{x}}{\sqrt{x}-2}\right]\div\frac{\sqrt{x}-1}{\sqrt{x}-2}\)

\(P=\left[\frac{x-\sqrt{x}+2}{\left(\sqrt{x}-2\right).\left(\sqrt{x}+1\right)}-\frac{\sqrt{x}.\left(\sqrt{x}+1\right)}{\left(\sqrt{x}-2\right).\left(\sqrt{x}+1\right)}\right]\times\frac{\sqrt{x}-2}{\sqrt{x}-1}\)

\(P=\left[\frac{x-\sqrt{x}+2-x-\sqrt{x}}{\left(\sqrt{x}-2\right).\left(\sqrt{x}+1\right)}\right]\times\frac{\sqrt{x}-2}{\sqrt{x}-1}\)

\(P=\left[\frac{-2\sqrt{x}+2}{\left(\sqrt{x}-2\right).\left(\sqrt{x}+1\right)}\right]\times\frac{\sqrt{x}-2}{\sqrt{x}-1}\)

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

\(P=\frac{-2}{\sqrt{x}+1}\)

Vậy \(P=\frac{-2}{\sqrt{x}+1}\)với \(x>0,x\ne1,x\ne4\)

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KO
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AH
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TN
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LT
27 tháng 5 2018 lúc 19:49

\(=\frac{\sqrt{x}}{\sqrt{x}-2}+\frac{\sqrt{x}-1}{\sqrt{x}+2}+\frac{\sqrt{x}-10}{\left(\sqrt{x}+2\right)\left(\sqrt{x}-2\right)}\)

\(=\frac{\sqrt{x}\left(\sqrt{x}+2\right)+\left(\sqrt{x}-1\right)\left(\sqrt{x}-2\right)+\left(\sqrt{x}-10\right)}{\left(\sqrt{x}-2\right)\left(\sqrt{x}+2\right)}\)

\(=\frac{x+2\sqrt{x}+x-2\sqrt{x}-\sqrt{x}+2+\sqrt{x}-10}{\left(\sqrt{x}+2\right)\left(\sqrt{x}-2\right)}\)

\(=\frac{2x-8}{x-4}\)

\(=\frac{2\left(x-4\right)}{x-4}\)

\(=2\)

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H24
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PB
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PB
11 tháng 8 2019 lúc 11:53

các bn ơi đoạn sau mik viết nhầm đấy bỏ phần không có ngặc đi nha

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PB
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MN
10 tháng 7 2020 lúc 11:21

a) \(A=\left(\frac{4\sqrt{x}}{\sqrt{x}+2}-\frac{8x}{x-4}\right):\left(\frac{\sqrt{x}-1}{x-2\sqrt{x}}-\frac{2}{\sqrt{x}}\right)\)

\(\Leftrightarrow A=\frac{4\sqrt{x}\left(\sqrt{x}-2\right)-8x}{\left(\sqrt{x}+2\right)\left(\sqrt{x}-2\right)}:\frac{\sqrt{x}-1-2\left(\sqrt{x}-2\right)}{\sqrt{x}\left(\sqrt{x}-2\right)}\)

\(\Leftrightarrow A=\frac{4x-8\sqrt{x}-8x}{\left(\sqrt{x}+2\right)\left(\sqrt{x}-2\right)}:\frac{\sqrt{x}-1-2\sqrt{x}+4}{\sqrt{x}\left(\sqrt{x}-2\right)}\)

\(\Leftrightarrow A=\frac{-4x-8\sqrt{x}}{\left(\sqrt{x}+2\right)\left(\sqrt{x}-2\right)}:\frac{-\sqrt{x}+3}{\sqrt{x}\left(\sqrt{x}-2\right)}\)

\(\Leftrightarrow A=\frac{-4\sqrt{x}}{\sqrt{x}-2}\cdot\frac{\sqrt{x}\left(\sqrt{x}-2\right)}{-\sqrt{x}+3}\)

\(\Leftrightarrow A=\frac{4x}{\sqrt{x}-3}\)

b) Để \(A=-1\)

\(\Leftrightarrow\frac{4x}{\sqrt{x}-3}=-1\)

\(\Leftrightarrow4x=3-\sqrt{x}\)

\(\Leftrightarrow4x+\sqrt{x}-3=0\)

\(\Leftrightarrow\left(\sqrt{x}+1\right)\left(4\sqrt{x}-3\right)=0\)

\(\Leftrightarrow\orbr{\begin{cases}\sqrt{x}+1=0\\4\sqrt{x}-3=0\end{cases}}\)

\(\Leftrightarrow\orbr{\begin{cases}\sqrt{x}=-1\left(ktm\right)\\\sqrt{x}=\frac{3}{4}\Leftrightarrow x=\frac{9}{16}\left(tm\right)\end{cases}}\)

Vậy để \(A=-1\Leftrightarrow x=\frac{9}{16}\)

c) Khi \(x=36\)

\(\Leftrightarrow A=\frac{4\cdot36}{\sqrt{36}-3}=\frac{144}{3}=48\)

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H24
23 tháng 11 2019 lúc 21:05

a) \(A=\left(\frac{4\sqrt{x}}{\sqrt{x}+2}-\frac{8x}{x-4}\right):\left(\frac{\sqrt{x}-1}{\left(x-2\sqrt{x}\right)}-\frac{2}{\sqrt{x}}\right)\)

\(A=\left(\frac{4\sqrt{x}}{\sqrt{x}+2}-\frac{8x}{\left(\sqrt{x}-2\right)\left(\sqrt{x}+2\right)}\right):\left(\frac{\sqrt{x}-1}{\sqrt{x}\left(\sqrt{x}-2\right)}-\frac{2}{\sqrt{x}}\right)\)

\(A=\left(\frac{4\sqrt{x}\left(\sqrt{x}-2\right)-8x}{\left(\sqrt{x}+2\right)\left(x-2\right)}\right):\left(\frac{\left(\sqrt{x}-1\right)-2\left(\sqrt{x}-2\right)}{\sqrt{x}\left(\sqrt{x}-2\right)}\right)\)

\(A=\left(\frac{4x-8\sqrt{x}-8x}{\left(\sqrt{x}+2\right)\left(\sqrt{x}\right)}\right):\left(\frac{\sqrt{x}-1-2\sqrt{x}+4}{\sqrt{x}\left(\sqrt{x}-2\right)}\right)\)

\(A=\left(\frac{-8\sqrt{x}-4x}{\left(\sqrt{x}+2\right)\sqrt{x}}\right):\left(\frac{3-\sqrt{x}}{\sqrt{x}\left(\sqrt{x}-2\right)}\right)\)

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

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

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

.......... Đến đây bạn tự nhân đa thức với đa thức xog rút gọn nha.

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H24
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NT
20 tháng 10 2023 lúc 18:43

a: \(P=\dfrac{\sqrt{x}-\left(\sqrt{x}-1\right)}{\sqrt{x}\left(\sqrt{x}-1\right)}:\dfrac{\left(\sqrt{x}+1\right)\left(\sqrt{x}-1\right)-\left(\sqrt{x}+2\right)\left(\sqrt{x}-2\right)}{\left(\sqrt{x}-2\right)\left(\sqrt{x}-1\right)}\)

\(=\dfrac{1}{\sqrt{x}\left(\sqrt{x}-1\right)}\cdot\dfrac{\left(\sqrt{x}-2\right)\left(\sqrt{x}-1\right)}{x-1-x+4}\)

\(=\dfrac{1}{\sqrt{x}}\cdot\dfrac{\sqrt{x}-2}{3}=\dfrac{\sqrt{x}-2}{3\sqrt{x}}\)

b: P=1/4

=>\(\dfrac{\sqrt{x}-2}{3\sqrt{x}}=\dfrac{1}{4}\)

=>\(4\left(\sqrt{x}-2\right)=3\sqrt{x}\)

=>\(4\sqrt{x}-8-3\sqrt{x}=0\)

=>\(\sqrt{x}=8\)

=>x=64

c: Khi \(x=4+2\sqrt{3}\) thì \(P=\dfrac{\sqrt{4+2\sqrt{3}}-2}{3\cdot\sqrt{4+2\sqrt{3}}}\)

\(=\dfrac{\sqrt{3}+1-2}{3\left(\sqrt{3}+1\right)}=\dfrac{\sqrt{3}-1}{3\sqrt{3}+3}=\dfrac{2-\sqrt{3}}{3}\)

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LK
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H24
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NT
20 tháng 10 2023 lúc 18:47

a: \(A=\dfrac{\sqrt{x}\left(\sqrt{x}-2\right)+2\sqrt{x}\left(\sqrt{x}+2\right)-3x-4}{x-4}\)

\(=\dfrac{x-2\sqrt{x}+2x+4\sqrt{x}-3x-4}{x-4}\)

\(=\dfrac{2\sqrt{x}-4}{x-4}=\dfrac{2}{\sqrt{x}+2}\)

b: A=1/2

=>\(\sqrt{x}+2=4\)

=>\(\sqrt{x}=2\)

=>x=4(loại)

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