Question

1). 3/√5
2). 3/2√5
3). 1/√12

Answer 1

$\sqrt{3}$ ≈ 1.732 
$\sqrt{5}$ ≈ 2.236 

$1. \frac{3}{\sqrt{5}} = \frac{3\sqrt{5}}{5} = \frac{3}{5}\sqrt{5} = 0.6 * 2.236 = 1.3416 \\ 2. \frac{3}{2\sqrt{5}} = \frac{3}{\sqrt{5}} * \frac{1}{2} = 1.3416 / 2 = 0.6708 \\ 3. \frac{1}{\sqrt{12}} = \frac{1}{2\sqrt{3}} = \frac{1}{\sqrt{3}} * \frac{1}{2} = \frac{\sqrt{3}}{3} * \frac{1}{2} = \frac{1.732}{3} * \frac{1}{2} = 0.866 / 3 = 0.2887$ 

Hope this may be helpful.