| Exam Board | Edexcel |
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| Module | FP1 (Further Pure Mathematics 1) |
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| Year | 2009 |
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| Session | January |
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| Topic | Proof by induction |
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4. Prove by induction that, for \(n \in \mathbb { Z } ^ { + }\),
$$\sum _ { r = 1 } ^ { n } \frac { 1 } { r ( r + 1 ) } = \frac { n } { n + 1 }$$