Làm gì thì làm cứ khử mẫu cái đã sau đó giải quyết từng vẫn đề 1 là xong. :D
`((5+2sqrt6)(49-20sqrt6)sqrt{5-2sqrt6})/(9sqrt3-11sqrt2)`
`=((5+2sqrt6)(49-20sqrt6)sqrt{5-2sqrt6}(9sqrt3+11sqrt2))/((9sqrt3)^2-(11sqrt2)^2)`
`=((5+2sqrt6)(49-20sqrt6)sqrt{5-2sqrt6}(9sqrt3+11sqrt2))/(243-242)`
`=(5+2sqrt6)(49-20sqrt6)sqrt{5-2sqrt6}(9sqrt3+11sqrt2)`
`=(5+2sqrt6)(49-20sqrt6)(9sqrt3+11sqrt2)sqrt{3-2sqrt{3.2}+2}`
`=(5+2sqrt6)(49-20sqrt6)(9sqrt3+11sqrt2)sqrt{(sqrt3-sqrt2)^2}`
`=(3+2sqrt6+2)(49-20sqrt6)(9sqrt3+11sqrt2)|sqrt3-sqrt2|`
`=(sqrt3+sqrt2)^2(49-20sqrt6)(9sqrt3+11sqrt2)(sqrt3-sqrt2)`
`=(sqrt3+sqrt2)(sqrt3-sqrt2)(sqrt3+sqrt2)(49-20sqrt6)(9sqrt3+11sqrt2)`
`=(3-2)(sqrt3+sqrt2)(49-20sqrt6)(9sqrt3+11sqrt2)`
`=(sqrt3+sqrt2)(9sqrt3+11sqrt2)(49-20sqrt6)`
`=(9.3+9sqrt6+11sqrt6+11.2)(49-20sqrt6)`
`=(27+22+20sqrt6)(49-20sqrt6)`
`=(49+20sqrt6)(49-20-sqrt6)`
`=49^2-(20sqrt6)^2`
`=2401-2400=1`.Đây số có đẹp không nào? :3
