Question

[Ling ling 2k7]

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

1) thu gọn P (đừng có làm tắt ạ=))))?)

2) Tính P biết \(x=3+2\sqrt{2}\)

Answer 1

[Lấp La Lấp Lánh]

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

\(=\dfrac{\left(\sqrt{x}-1\right)\left(\sqrt{x}+1\right)}{\sqrt{x}\left(\sqrt{x}-1\right)}.\dfrac{\left(\sqrt{x}-1\right)\left(\sqrt{x}+1\right)}{\sqrt{x}-1}=\dfrac{\left(\sqrt{x}+1\right)^2}{\sqrt{x}}\)

2) \(P=\dfrac{\left(\sqrt{x}+1\right)^2}{\sqrt{x}}=\dfrac{\left(\sqrt{3+2\sqrt{2}}+1\right)^2}{\sqrt{3+2\sqrt{2}}}\)

\(=\dfrac{\left(\sqrt{\left(\sqrt{2}+1\right)^2}+1\right)^2}{\sqrt{\left(\sqrt{2}+1\right)^2}}=\dfrac{\left(\sqrt{2}+2\right)^2}{\sqrt{2}+1}=\dfrac{2+4+4\sqrt{2}}{\sqrt{2}+1}=\dfrac{6+4\sqrt{2}}{\sqrt{2}+1}\)