Bài 3:
a) \(P=\left(\dfrac{3x-2}{x-4}-\dfrac{\sqrt{x}}{\sqrt{x}+2}-\dfrac{2\sqrt{x}}{\sqrt{x}-2}\right):\dfrac{1}{\sqrt{x}+2}\left(đk:x\ge0,x\ne4\right)\)
\(=\dfrac{3x-2-\sqrt{x}\left(\sqrt{x}-2\right)-2\sqrt{x}\left(\sqrt{x}+2\right)}{\left(\sqrt{x}-2\right)\left(\sqrt{x}+2\right)}.\dfrac{\sqrt{x}+2}{1}\)
\(=\dfrac{3x-2-x+2\sqrt{x}-2x-4\sqrt{x}}{\sqrt{x}-2}=\dfrac{-2\sqrt{x}-2}{\sqrt{x}-2}\)
b) \(P=\dfrac{-2\sqrt{x}-2}{\sqrt{x}-2}=\dfrac{5}{2}\)
\(\Rightarrow-4\sqrt{x}-4=5\sqrt{x}-10\)
\(\Rightarrow9\sqrt{x}=6\Rightarrow\sqrt{x}=\dfrac{6}{9}\Rightarrow x=\dfrac{36}{81}\left(tm\right)\)
\(2,\\ a,=1-\sqrt{2}+3-\sqrt{2}=4-2\sqrt{2}\\ b,=\left|3a\right|-\left|4a\right|+\left|2a\right|=-3a+4a-2a=-a\\ c,=\dfrac{a}{b}\left|\dfrac{ab}{4}\right|=\dfrac{a}{b}\cdot\dfrac{ab}{4}=\dfrac{a^2}{4}\\ d,=xy^2\left|\dfrac{x}{y^2}\right|=\dfrac{x^2y^2}{y^2}=x^2\)
Bài 2:
a) \(=\sqrt{2}-1+2+9-6\sqrt{2}=10-5\sqrt{2}\)
b) \(=3\left|a\right|-4\left|a\right|+2\left|a\right|=\left|a\right|=-a\)
c) \(=\dfrac{a}{b}.\dfrac{\left|ab\right|}{2}=\dfrac{a^2}{2}\)
d) \(=xy^2.\dfrac{\left|x\right|}{y^2}=-x^2\)
