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by thejteam
4534 days ago
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A very informal proof: Let X = 0.999…
Then 10X = 9.999… 10X - X = 9.999… - 0.999… = 9 = 9X
Therefore X = 1. Being able to do the subtraction infinitely is a little hand-wavy, but should suffice as a demo for middle and high schoolers. More formal proofs involve limits that one wouldn't normally encounter until a course in real analysis. Wikipedia has a whole page devoted to the topic:
http://en.wikipedia.org/wiki/0.999... |
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