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#1
02-07-2005, 03:46 PM
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Calling math wizards (that means you!)
Working on some pre-calculus here, not too challenging for the math inclined.
 I must be doing something wrong, because we haven't discussed imaginary numbers as a possible answer for a natural logarithm.  You can see how far I got, I eliminated the ln's, but I have that fraction to deal with now.  Calculator says this, not sure how it got there though. Help please!
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#2
02-07-2005, 04:01 PM
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Re: Calling math wizards (that means you!)
Where's Tangie?
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*~*KaTe *~* We know exactly where the one cow with mad-cow-disease is located among the millions and millions of cows in America, but we don't have a clue as to where the thousands of illegal immigrants and terrorists are located. Maybe we should put the Department of Agriculture in charge of immigration.
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#4
02-07-2005, 04:29 PM
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Re: Calling math wizards (that means you!)
I could have answered this in 10 seconds 5 years ago. Today i haven't got a clue.
And yes, i do realise this reply is of absolutely no use to you 
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#5
02-07-2005, 04:30 PM
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Re: Calling math wizards (that means you!)
Brain.....too....rusty....with....logarithms. Sorry.
I could be wrong, but can't you take a number to a negative power in the numerator and put it into the denominator with a positive power? I seem to recall that's the easy way to get rid of a negative power. So your e^-48 = -68 turns into: 1 / e^48 = -68
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Ours: 2020 Jeep Wrangler 2.0, 53k 2013 Toyota FJ Cruiser, 84k Kids: 2005 Honda CRV, 228k
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#6
02-07-2005, 04:40 PM
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Re: Re: Calling math wizards (that means you!)
Quote:
I'm gonna have to blame my handwriting on this. it's -4X, not -48
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#7
02-07-2005, 04:54 PM
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Re: Calling math wizards (that means you!)
haha... there wouldnt have been anything to solve for if it was an 8... kinda worrying, fredjacksonsan
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#8
02-07-2005, 06:20 PM
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Re: Calling math wizards (that means you!)
Okay, I'm coming up with the -4x = ln -68 as well, so you aren't alone. You can't take the natual log of a negative #. I must be stupid, on top of that... is it safe to assume that the second problem that you have entered on your calculator is a separate problem? Cause I have no idea how you got from the first problem to that problem.
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Like a boy - but BETTER! 2005 Subaru Forester 2.5X 1997 Honda Civic EX Coupe Inform yourself: AF User Guidelines
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#9
02-07-2005, 06:21 PM
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Re: Calling math wizards (that means you!)
tangie to the rescue
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*~*KaTe *~* We know exactly where the one cow with mad-cow-disease is located among the millions and millions of cows in America, but we don't have a clue as to where the thousands of illegal immigrants and terrorists are located. Maybe we should put the Department of Agriculture in charge of immigration.
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#10
02-07-2005, 06:26 PM
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Re: Calling math wizards (that means you!)
Tangie, yes, it's a seperate problem.
If I were to divide -4x = ln -68 by -1 to change the signs, It wouldn't affect the -68 would it? I believe I would get 4x = - ln -68, correct? edit: 1500th post w00t.
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#11
02-07-2005, 06:30 PM
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Re: Calling math wizards (that means you!)
Right, you'd just be changing the sign of the whole RS of the equation. Give me a second on that second problem, now that I know I'm not insane.
__________________
Like a boy - but BETTER! 2005 Subaru Forester 2.5X 1997 Honda Civic EX Coupe Inform yourself: AF User Guidelines
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#12
02-07-2005, 06:45 PM
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Re: Calling math wizards (that means you!)
Okay, here's the deal... You can solve the second problem down to a cubic (use basic algebra skills). From there, I honestly just graphed it, and found the X intercept, which is of course, a solution to the cubic. The cubic you get from solving is not "factorable", so I chose to graph it to find the solution.
__________________
Like a boy - but BETTER! 2005 Subaru Forester 2.5X 1997 Honda Civic EX Coupe Inform yourself: AF User Guidelines
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#13
02-07-2005, 06:56 PM
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Re: Calling math wizards (that means you!)
Tangie, Cubic equation is x^3 - 2x^2 - x -1, with solution of 2.54, which is correct. The reason that I didn't solve into a cubic equation sooner was because we've never discussed getting cubics from log problems. We've had quadratics, but not cubics.
Anyhow, thanks.
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#14
02-07-2005, 07:06 PM
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Re: Calling math wizards (that means you!)
check the related links
 loledit: d'oh! they used to be for a bunch of 4th grade math software
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#15
02-07-2005, 07:10 PM
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Re: Re: Calling math wizards (that means you!)
Quote:
Anyhoo, Isn't there some rule about taking the Ln of -e^any power? I should know this, but I need to spend some time grading papers instead of working on this. Sorry.
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Like a boy - but BETTER! 2005 Subaru Forester 2.5X 1997 Honda Civic EX Coupe Inform yourself: AF User Guidelines
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