[tex]\lim_{x\rightarrow 0}\frac{\sqrt{1+2x}(\sqrt[3]{1+4x}-1)+\sqrt{1+2x}-1}{x}=\lim_{x\rightarrow 0}\frac{\sqrt{1+2x}\left ( \frac{4x}{\sqrt[3]{(1+4x)^2}+\sqrt[3]{1+4x}+1} \right )+\frac{2x}{\sqrt{1+2x}+1}}{x}=\lim_{x \rightarrow 0} \left (\frac{4\sqrt{1+2x}}{\sqrt[3]{(4x+1)^2}+\sqrt[3]{1+4x}+1} +\frac{2}{\sqrt{1+2x}+1}\right )=\frac{4}{3}+\frac{2}{2}=\frac{7}{3}[/tex]