9231 P11 - Nov 2025 - Q1 - 9 marks
5881
(a) Use standard results from MF19 to find \(\sum_{r=1}^{n}(8r^3+12r^2+4r+3)\) in terms of \(n\), simplifying your answer.
(b) Show that \(\frac1{r^4}-\frac1{(r+1)^4}=\frac{4r^3+6r^2+4r+1}{r^4(r+1)^4}\), and hence find \(\sum_{r=1}^{n}\frac{4r^3+6r^2+4r+1}{r^4(r+1)^4}\).
(c) Deduce the value of \(\sum_{r=1}^{\infty}\frac{4r^3+6r^2+4r+1}{r^4(r+1)^4}\).
Solutions locked. Please sign in with access to view them.