Question 7 - A-Level Maths

Exam Board	OCR MEI
Module	FP1 (Further Pure Mathematics 1)
Year	2008
Session	June
Topic	Sequences and series, recurrence and convergence

Show that \(\frac { 1 } { 3 r - 1 } - \frac { 1 } { 3 r + 2 } \equiv \frac { 3 } { ( 3 r - 1 ) ( 3 r + 2 ) }\) for all integers \(r\).
Hence use the method of differences to find \(\sum _ { r = 1 } ^ { n } \frac { 1 } { ( 3 r - 1 ) ( 3 r + 2 ) }\). Section B (36 marks)