[tex]\left(\dfrac{3}{\sqrt5}\right)\left(\dfrac{4}{\sqrt3}\right)=\dfrac{3\cdot4}{\sqrt5\cdot\sqrt3}=\dfrac{12}{\sqrt{5\cdot3}}=\dfrac{12}{\sqrt{15}}\\\\=\dfrac{12\cdot\sqrt{15}}{\sqrt{15}\cdot\sqrt{15}}=\dfrac{12\sqrt{15}}{15}=\dfrac{12\sqrt{15}:3}{15:3}=\dfrac{4\sqrt{15}}{5}[/tex]
[tex]Used:\\\\\sqrt{a}\cdot\sqrt{b}=\sqrt{ab}\\\\\sqrt{a}\cdot\sqrt{a}=a[/tex]
