Đáp án:
Giải thích các bước giải:
4) `\frac{3-\sqrt{3}}{2\sqrt{3}-2}+\frac{\sqrt{6}+\sqrt{3}}{2\sqrt{2}+2}`
`= \frac{\sqrt{3}(\sqrt{3}-1)}{2.(\sqrt{3}-1)}+\frac{\sqrt{3}.(\sqrt{2}+1)}{2.(\sqrt{2}+1)}`
`=\frac{\sqrt{3}}{2}+\frac{\sqrt{3}}{2}`
`=\frac{2\sqrt{3}}{2}`
`=\sqrt{3}`
5) `\frac{1}{\sqrt{5}-1}-\frac{1}{\sqrt{5}+1}`
`=\frac{\sqrt{5}+1}{4}-\frac{\sqrt{5}-1}{4}`
`=\frac{1}{2}`
6) `\frac{1}{\sqrt{5}-2}+\frac{1}{\sqrt{5}+2}`
`=\frac{\sqrt{5}+2}{1}+\frac{\sqrt{5}-2}{1}`
`=\sqrt{5}+2+\sqrt{5}-2`
`=2\sqrt{5}`
