2022 NJC P1 Q6
2022 NJC P1 Q6 (i) By considering ${{u}_{k}}-{{u}_{k+1}}$, where ${{u}_{k}}=frac{1}{k!}$, find $frac{3}{4!}+frac{4}{5!}+frac{5}{6!}+…+frac{3n+2}{left( 3n+3 right)!}$ in terms of $n$. [4] (ii) Find $sumlimits_{r=5}^{3n+3}{frac{r-1}{r!}}$. Hence show that $sumlimits_{r=5}^{3n+3}{frac{3}{r!}<frac{1}{24}}$. [4] Suggested Video and