`y10000`
`a )`
`M = \sqrt{36} + \sqrt{18} - \sqrt{8} - \sqrt{2}`
`M = 6 + 3\sqrt{2} - 2\sqrt{2} - \sqrt{2}`
`M = 6`
`b )`
$\text{ĐK : x ≠ 1 và x > 0}$
`D=(\frac{\sqrt{x}}{\sqrt{x}-1}+\frac{\sqrt{x}}{\sqrt{x}+1}).\frac{x-1}{\sqrt{4x}`
`D=(\frac{\sqrt{x}(\sqrt{x}+1)+\sqrt{x}(\sqrt{x}-1)}{x-1}).\frac{x-1}{2\sqrt{x}}`
`D=(\frac{x+\sqrt{x}+x-\sqrt{x}}{x-1}).\frac{x-1}{2\sqrt{x}`
`D=\frac{2x}{x-1}.\frac{x-1}{2\sqrt{x}`
`D=\sqrt{x}`