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Topic: An Exponential Curiosity (Read 413 times) |
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Sir Col
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Clearly x2/6 = x1/3, or does it? As x2/6 = (x1/6)2 = (x2)1/6... (-1)1/3 = -1, (1[pm][smiley=i.gif][surd]3)/2 [three values] ((-1)1/6)2 = -1, (1[pm][smiley=i.gif][surd]3)/2 However, ((-1)2)1/6 = -1, (1[pm][smiley=i.gif][surd]3)/2, but also 1, -(1[pm][smiley=i.gif][surd]3)/2 [six values] Consider the two graphs below: (i) y = x1/3, (ii) y = (x2)1/6. Spot the difference? [e]Thanks for the correction, rmsgrey.[/e]
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« Last Edit: Jan 29th, 2005, 3:11pm by Sir Col » |
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rmsgrey
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Re: An Exponential Curiosity
« Reply #1 on: Jan 29th, 2005, 2:12pm » |
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on Jan 29th, 2005, 10:19am, Sir Col wrote: ((-1)1/6)2 (has six complex values) |
| I get [pm]i6=-1 and that: ((-1)1/6)2=-1 (and 2 complex values)=(-1)1/3
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Icarus
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Re: An Exponential Curiosity
« Reply #2 on: Jan 29th, 2005, 9:02pm » |
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Impudent monkey indeed. You know very well that exponentiation cannot be extended to domains completely encircling 0 in the complex plane. Yet that is exactly what you attempt here!
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"Pi goes on and on and on ... And e is just as cursed. I wonder: Which is larger When their digits are reversed? " - Anonymous
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Sir Col
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Re: An Exponential Curiosity
« Reply #3 on: Jan 30th, 2005, 2:15am » |
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Cheeky by name, cheeky by nature... But what about the real graphs? Why is the graph of y = (x2)1/6 different to y = x1/3, when (x2)1/6 = x2/6 = x1/3? Does that mean that 2/6 is not equal to 1/3?
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Barukh
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Re: An Exponential Curiosity
« Reply #4 on: Jan 30th, 2005, 6:26am » |
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on Jan 30th, 2005, 2:15am, Sir Col wrote:But what about the real graphs? Why is the graph of y = (x2)1/6 different to y = x1/3, when (x2)1/6 = x2/6 = x1/3? Does that mean that 2/6 is not equal to 1/3? |
| Why complicate the question? Consider two functions: (i) y = x; (ii) y = [sqrt](x2)
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Icarus
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Re: An Exponential Curiosity
« Reply #5 on: Jan 30th, 2005, 11:24am » |
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More to the point, that (xa)b = xab rule comes with an "x [ge] 0" qualifier.
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« Last Edit: Jan 31st, 2005, 4:11pm by Icarus » |
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"Pi goes on and on and on ... And e is just as cursed. I wonder: Which is larger When their digits are reversed? " - Anonymous
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