A-LevelFurther MathematicsSummation of series9231/12 · May/June 2016 · Q26 Marks
Express 4/(r(r + 1)(r + 2)) in partial fractions and hence find sum from r=1 to n of 4/(r(r + 1)(r + 2)). Deduce the value of sum from r=1 to infinity of 4/(r(r + 1)(r + 2)).
- Express 4/(r(r + 1)(r + 2)) in partial fractions and hence find sum from r=1 to n of 4/(r(r + 1)(r + 2)).[5]
- Deduce the value of sum from r=1 to infinity of 4/(r(r + 1)(r + 2)).[1]
Mark scheme
Marking points from the official mark scheme (May/June 2016). The mark or mark type is shown in brackets.
- [M1A1] 2/r - 4/(r+1) + 2/(r+2) (Award B2 if written down by cover up rule.)
- [M1A1] 1 - 2/(n+1) + 2/(n+2) (AEF)
- [B1] Sum to infinity = 1
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