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Inverse of exponential function 
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#1
Sep1711, 07:16 AM

P: 3

1. The problem statement, all variables and given/known data
Give the inverse of this function N=f(L)=18^{168L} The answer has to be filled in in Maple 2. Relevant equations 3. The attempt at a solution N=18^{168L} 168L=ln(N)/ln(18) 8L=(ln(N)/ln(18))16 L=ln(N)/(8*ln(18))+2 Is this correct? When i fill this in in maple it's incorrect. I've really no clue why it is wrong. 


#2
Sep1711, 08:09 AM

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P: 10,541

L=ln(N)/(8*ln(18))+2 is the same function as the original. Choose L the independent variable and N the dependent one. (Just exchange L and N).
ehild 


#3
Sep1711, 08:12 AM

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Yes it's correct. What are you typing into maple exactly? Your syntax is probably slightly off.
edit: Sorry I didn't notice that you forgot to swap your variables. 


#4
Sep1711, 09:13 AM

P: 3

Inverse of exponential function
thanks! It's also mentioned that it should be simplified as much as possible.
Does that mean that the 8*LN(18) could be simplified to 8*LN(2*9) and more? 


#5
Sep1711, 10:08 AM

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It's as simple as it can get, unless you believe [itex]\ln{\frac{1}{x}}[/itex] is more simple than [itex]\ln{x}[/itex] you shouldn't be changing anything.
[itex]\ln{18}[/itex] is definitely more desirable than [itex]\ln{9\cdot2}[/itex] 


#6
Sep1711, 12:06 PM

Sci Advisor
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P: 5,027

That annoying É is actually a question mark, but when I type it in it gives me that accented E; that only seems to happen when I access this website through Google Chrome! RGV 


#7
Sep1711, 05:27 PM

P: 3

The point is, that i can't see why the answer was wrong. I have 2 chances, so for the second change i will try to swap the variables. 


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