Answer
$-6-3\sqrt{5}$
Work Step by Step
We simplify the fraction by multiplying through by $2+\sqrt{5}$ and using the fact that $(a-b)(a+b)=a^2-b^2$:
$\displaystyle \frac{3}{2-\sqrt{5}}=\frac{3(2+\sqrt{5})}{(2+\sqrt{5})(2-\sqrt{5})}=\frac{6+3\sqrt{5}}{4-5}=-6-3\sqrt{5}$
