\(\frac{4\sqrt{18}}{\sqrt{8}}\\ = \frac{4\sqrt{9\times 2}}{\sqrt{4 \times 2}} = \frac{12\sqrt{2}}{2\sqrt{2}}=\frac{6\sqrt{2}}{\sqrt{2}}\\ Rationalising \frac{6\sqrt{2}}{\sqrt{2}}\\ =\frac{6\sqrt{2}}{\sqrt{2}} \times \frac{\sqrt{2}}{\sqrt{2}} = 6\)