lean_workbook_plus_729

Solution: \n The induction step is: \n $2\sqrt{n}+\frac{1}{\sqrt{n+1}}\leq2\sqrt{n+1}$ $\Leftrightarrow2\sqrt{n^{2}+n}+1\leq2n+2$ $\Leftrightarrow2\sqrt{n^{2}+n}\leq2n+1$ $\Leftrightarrow4n^{2}+4n\leq4n^{2}+4n+1$