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

`+` `=> (2\sqrt{3})/(\sqrt{3 - 1}) = (2\sqrt{3})/(\sqrt{2}) . sqrt{2}/sqrt{2} = \sqrt{6}`

`+` `=> \sqrt x + \sqrt{3x} + \sqrt{4x} = \sqrt x(1 + \sqrt 3 + 2) = \sqrt x(3 + \sqrt{3})`

`=> \sqrt x(3 + \sqrt{3}) = \sqrt{6} => \sqrt x = \sqrt{6}/(3 + \sqrt{3})`

`=> \sqrt x = (\sqrt{6}(3 - \sqrt{3}))/((3 + \sqrt{3})(3 - \sqrt{3})) = (\sqrt6 - \sqrt 2)/2`

`=> x = ((\sqrt6 - \sqrt 2)/2)^2 = (8 - 4\sqrt 3)/ 4`

`=> x = 2 - \sqrt3`

Vậy nghiệm của pt là `x = 2 - \sqrt3`

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