A=căn 9 -4 căn 5 + 1 phần căn 5 -2

P=(2x1-x2)(2x2-x1)

A=2 căn 4 - 2 căn 3 - 1 phần 2 căn 48

`A=\sqrt{9}-4\sqrt{5}+1/\sqrt{5}-2`

`=3-4\sqrt{5}+(1.\sqrt{5})/(\sqrt{5}.\sqrt{5})-2`

`=1-4\sqrt{5}+\sqrt{5}/5`

`=1-4/\sqrt{5}+1/5 .\sqrt{5}`

`=1-19/5\sqrt{5}`

------------------------------------------

`P=(2x_1-x_2)(2x_2-x_1)`

`=4x_1x_2-2(x_2)^2-2(x_1)^2-x_2x_1`

----------------------------------------------

`A=2\sqrt{4}-2\sqrt{3}-1/(2\sqrt{48})`

`=2\sqrt{4}-2\sqrt{3}-1/(2.\sqrt{2^4.3})`

`=2\sqrt{4}-2\sqrt{3}-1/(2.\sqrt{2^4}.\sqrt{3})`

`=2\sqrt{4}-2\sqrt{3}-1/(2.2^2.\sqrt{3})`

`=2\sqrt{4}-2\sqrt{3}-1/(8\sqrt{3})`

`=2\sqrt{4}-2\sqrt{3}-(1.\sqrt{3})/(8\sqrt{3}.\sqrt{3})`

`=2\sqrt{4}-2\sqrt{3}-\sqrt{3}/(8.3)`

`=2\sqrt{4}-2\sqrt{3}-\sqrt{3}/24`

`=2\sqrt{4}-2\sqrt{3}-1/24 .\sqrt{3}`

`=2\sqrt{4}-(2\sqrt{3}-1/24 .\sqrt{3})`

`=2\sqrt{4}-47/24\sqrt{3}`