The first expression is [tex] 4 \times \sqrt {\frac{16}{36}} [/tex]
=[tex] 4 \times {\frac{4}{6}} [/tex]
=[tex] \frac{16}{6} [/tex]
Reducing it to the lowest form,
=[tex] \frac{8}{3} [/tex]
The second expression is [tex] 5\sqrt{18x} \times 2\sqrt{6x^{3}} [/tex]
=[tex] 5\times 3\sqrt{2x} \times 2\times \sqrt{2} \sqrt{3} x^{\frac{3}{2}} [/tex]
=[tex] 15 \times (\sqrt{2} \times \sqrt{2}) \times 2 \times \sqrt{3}\sqrt{x} x^{\frac{3}{2}} [/tex]
=[tex] 60\sqrt{3} x^{\frac{1}{2}+\frac{3}{2}} [/tex]
=[tex] 60\sqrt{3} x^2 [/tex]
