| Exam Board | OCR MEI |
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| Module | Further Pure Core AS (Further Pure Core AS) |
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| Year | 2019 |
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| Session | June |
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| Topic | Proof by induction |
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5 Prove by induction that, for all positive integers \(n , \sum _ { r = 1 } ^ { n } \frac { 1 } { 3 ^ { r } } = \frac { 1 } { 2 } \left( 1 - \frac { 1 } { 3 ^ { n } } \right)\).