[tex]3(\sqrt{5})^{2} = 3*5 = 15\\\\3\sqrt{2} * 5\sqrt{2} = (3+5)\sqrt{2} =8\sqrt{2}[/tex]
[tex](\frac{3}{5}\sqrt{10} )^{2} = (\frac{3\sqrt{10} }{5})^{2} = \frac{9*10}{25} =\frac{9*2}{5} =\frac{18}{5}[/tex]
