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   An Exponential Curiosity
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Sir Col
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An Exponential Curiosity   exponential_graph.gif
« on: Jan 29th, 2005, 10:19am »
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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?  Wink
 
 
 
[e]Thanks for the correction, rmsgrey.[/e]
« Last Edit: Jan 29th, 2005, 3:11pm by Sir Col » IP Logged


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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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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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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? Roll Eyes
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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? Roll Eyes

Why complicate the question? Consider two functions: (i) y = x; (ii) y = [sqrt](x2)
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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.
« Last Edit: Jan 31st, 2005, 4:11pm by Icarus » IP Logged

"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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