[tex]\frac{6}{4-\sqrt{5}}[/tex]
multiply numerator and denominator by the conjugate of the denominator 4+sqrt(5)
[tex]=\frac{6(4+\sqrt{5})}{(4-\sqrt{5})(4+\sqrt{5})}[/tex]
[tex]=\frac{24+6\sqrt{5}}{16-5}[/tex]
[tex]=\frac{24+6\sqrt{5}}{11}[/tex]
[tex]=\frac{24}{11}+\frac{6\sqrt{5}}{11}[/tex]