[tex] \frac{ \sqrt{3x}-4}{ \sqrt{3x}+4}= \frac{ \sqrt{3x}-4}{ 4+\sqrt{3x}}=\frac{ (\sqrt{3x}-4)(4- \sqrt{3x} )}{ (4+\sqrt{3x})(4- \sqrt{3x})}= \\ \\ = \frac{4\sqrt{3x}-16-3x+4\sqrt{3x}}{16-3x}= \frac{8\sqrt{3x}-3x-16}{16-3x} \\ \\ Amlificarea \;asta\;se \;numeste\; \bold{rationalizarea\; numitorului} [/tex]