a) [tex]\frac{1}{\sqrt{7} } * \frac{\sqrt{7} }{\sqrt{7} } = \frac{\sqrt{7} }{7}[/tex]
b) [tex]\frac{1}{4\sqrt{5} } * \frac{\sqrt{5} }{\sqrt{5} } = \frac{\sqrt{5} }{4 * 5} = \frac{\sqrt{5} }{20}[/tex]
c) [tex]\frac{6\sqrt{2} }{\sqrt{3} } * \frac{\sqrt{3} }{\sqrt{3} } = \frac{6\sqrt{6} }{3} = 2\sqrt{6}[/tex]
