Đáp án+Giải thích các bước giải:
`\sqrt{(3\sqrt{2}-2005)^2}+\sqrt{18}`
`=|3\sqrt{2}-2005|+3\sqrt{2}`
`=2005-3\sqrt{2}+3\sqrt{2}`
`=2005`
`P=(\frac{1}{\sqrt{a}-1}-\frac{1}{\sqrt{a}}):(\frac{\sqrt{a}+1}{\sqrt{a}-2}-\frac{\sqrt{a}+2}{\sqrt{a}-1})(a>0,a\ne1,\ne4)`
`=(\frac{\sqrt{a}-\sqrt{a}+1}{\sqrt{a}(\sqrt{a}-1)}):(\frac{(\sqrt{a}-1)(\sqrt{a}+1)-(\sqrt{a}+2)(\sqrt{a}-2)}{(\sqrt{a}-1)(\sqrt{a}-2)})`
`=\frac{1}{\sqrt{a}(\sqrt{a}-1)}.\frac{(\sqrt{a}-1)(\sqrt{a]-2)}{a-1-a+4}`
`=\frac{(\sqrt{a}-1)(\sqrt{a}-2)}{\sqrt{a](\sqrt{a]-1).3}`
`=\frac{\sqrt{a}-2}{3\sqrt{a}}`