Đáp án:
`n)N=3-7\sqrt{3}`
Giải thích các bước giải:
`n)N=6/(1-\sqrt{3})-(2\sqrt{3})/(2+\sqrt{3})`
`=[6(1+\sqrt{3})]/[(1-\sqrt{3})(1+\sqrt{3})]-(2\sqrt{3}(2-\sqrt{3}))/[(2+\sqrt{3})(2-\sqrt{3})]`
`=[6(1+\sqrt{3})]/(1^2-(\sqrt{3})^2)-(2\sqrt{3}(2-\sqrt{3}))/(2^2-(\sqrt{3})^2)`
`=[6(1+\sqrt{3})]/(1-3)-(2\sqrt{3}(2-\sqrt{3}))/(4-3)`
`=[6(1+\sqrt{3})]/(-2)-(2\sqrt{3}(2-\sqrt{3}))/1`
`=-3(1+\sqrt{3})-2\sqrt{3}(2-\sqrt{3})`
`=-3-3\sqrt{3}-4\sqrt{3}+6`
`=(-3+6)-(3\sqrt{3}+4\sqrt{3})`
`=3-7\sqrt{3}`
