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November 3rd, 2017, 10:23 AM   #1
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Solve. Answer only the positive solution.

Unless this is too hard to explain for me here I just need steps for where to go from when I get the 2.56E-6

in order to get it to a fraction. Thanks for any reply even if I can't have a shown process.
Attached Images new1.PNG (4.0 KB, 3 views) November 3rd, 2017, 11:17 AM   #2
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Quote:
 Originally Posted by GIjoefan1976 Unless this is too hard to explain for me here I just need steps for where to go from when I get the 2.56E-6 in order to get it to a fraction. Thanks for any reply even if I can't have a shown process.
$13 + 0.0005x^{-4} = 208.3125 \implies 0.0005x^{-4} = 195.3125 \implies \dfrac{0.005}{x^4} = 195.3125 \implies$

$x^4 = \dfrac{0.0005}{195.3125} = \dfrac{5 * 10^{-4}}{1.953125 * 10^2} = 2.56 * 10^{-6}.$

I take it that this is what you did. Well done. (It really does help to show what you have done so we we do not have to do work that is already done.)

Your problem here is that minus 6 is not divisible by 4. You need a simple trick: you multiply by 1.

$x^4 = 2.56 * 10^{-6} = 2.56 * 10^2 * 10^{-2} * 10^{-6} = 256 * 10^{-8} \implies.$

$x = \sqrt{256 * 10^{-8}} = \sqrt{256} * \sqrt{10^{-8}} = 4 * 10^{-2} = \dfrac{4}{100} = \dfrac{1}{25}.$ November 3rd, 2017, 12:13 PM   #3
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Quote:
 Originally Posted by JeffM1 $13 + 0.0005x^{-4} = 208.3125 \implies 0.0005x^{-4} = 195.3125 \implies \dfrac{0.005}{x^4} = 195.3125 \implies$ $x^4 = \dfrac{0.0005}{195.3125} = \dfrac{5 * 10^{-4}}{1.953125 * 10^2} = 2.56 * 10^{-6}.$ I take it that this is what you did. Well done. (It really does help to show what you have done so we we do not have to do work that is already done.) Your problem here is that minus 6 is not divisible by 4. You need a simple trick: you multiply by 1. $x^4 = 2.56 * 10^{-6} = 2.56 * 10^2 * 10^{-2} * 10^{-6} = 256 * 10^{-8} \implies.$ $x = \sqrt{256 * 10^{-8}} = \sqrt{256} * \sqrt{10^{-8}} = 4 * 10^{-2} = \dfrac{4}{100} = \dfrac{1}{25}.$
hello Jeffm1! Okay thanks very much...okay I will make sure to share the previous work from now on. I am still lost for where the 10^{6} came from? Is that just coming from the fact that we have two decimal places after the . so we have to use 100? November 3rd, 2017, 09:05 PM #4 Senior Member   Joined: May 2016 From: USA Posts: 1,310 Thanks: 551 Let's start by cleaning up my first post. $13 + 0.0005x^{-4} = 208.3125$ $\implies 0.0005x^{-4} = 195.3125$ $\implies \dfrac{5 * 10^{-4}}{x^4} = 1.953125 * 10^2$ $\implies x^4 = \dfrac{5 * 10^{-4}}{1.953125 * 10^2} = 2.56 * 10^{(-\ 4 - 2)} = 2.56 * 10^{-6}.$ Is this what you did? If so, great. Now your second post asked where 10^6 came from? It does not come from anywhere because it is no where in the working. Are you ok up to here? The problem in proceeding is that minus 6 is not divisible by 4. You need a simple trick: you multiply by $1 = 10^0 = 10^{(2-2)} = 10^2 * 10^{-2}.$ Why 2 - 2? Because $-\ 6 - 2 = -\ 8 = 4(-\ 2).$ $x^4 = 2.56 * 10^{-6} = 2.56 * 10^2 * 10^{-2} * 10^{-6} = 2.56 * 100 * 10^{-8} = 256 * 10^{-8}.$ Any questions up to here? If so, where exactly? $\therefore x = \sqrt{256 * 10^{-8}} = \sqrt{256} * \sqrt{10^{-8}} = 4 * 10^{-2} = \dfrac{4}{100} = \dfrac{1}{25}.$ Sorry for the bad formatting in the first post. Now that it is easier to read, do you still have questions? Tags answer, positive, solution, solve Thread Tools Show Printable Version Email this Page Display Modes Linear Mode Switch to Hybrid Mode Switch to Threaded Mode Similar Threads Thread Thread Starter Forum Replies Last Post mick17 Abstract Algebra 8 September 1st, 2015 04:09 AM FreaKariDunk Real Analysis 2 November 19th, 2012 12:30 PM HellBunny Algebra 6 April 22nd, 2012 12:38 PM ultramegasuperhyper Number Theory 4 June 5th, 2011 05:07 PM nooblet Number Theory 4 March 18th, 2009 08:34 PM

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