Đáp án:
Giải thích các bước giải:
Bài 2:
`A=(\sqrt{2}+1)^2+\frac{4}{3}.\sqrt{18}-\frac{5}{\sqrt{2}+1}`
`A=3+2\sqrt{2}+4\sqrt{2}-5(\sqrt{2}-1)`
`A=3+2\sqrt{2}+4\sqrt{2}-5\sqrt{2}+5`
`A=8+\sqrt{2}`
`B=\frac{2}{\sqrt{3}-1}-\frac{4}{\sqrt{5}-1}+\frac{2}{\sqrt{5}-\sqrt{3}}`
`B=\frac{2.(\sqrt{3}+1)}{2}-\frac{4.(\sqrt{5}+1)}{4}+\frac{2.(\sqrt{5}+\sqrt{3})}{2}`
`B=\sqrt{3}+1-\sqrt{5}-1+\sqrt{5}+\sqrt{3}`
`B=2\sqrt{3}`
`C=\sqrt{14+4\sqrt{6}}-\sqrt{9-4\sqrt{2}}`
`C=\sqrt{(2\sqrt{3}+\sqrt{2})^2}-\sqrt{(2\sqrt{2}-1)^2}`
`C=|2\sqrt{3}+\sqrt{2}|-|2\sqrt{2}-1|`
`C=2\sqrt{3}+\sqrt{2}+1-2\sqrt{2}`
`C=2\sqrt{3}-\sqrt{2}+1`
