Literal equations that can't be solved?

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dipetersen
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Literal equations that can't be solved?

Postby dipetersen » Wed Oct 05, 2011 1:48 am

I have a literal equation that I am supposed to solve for 'a' but I think it is an equation that can't be rewritten. Can someone confirm this for me?

x=(a+b+c)/ab solve for a

I say it can't be solved. Am I wrong?
Thanks

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stapel_eliz
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Postby stapel_eliz » Wed Oct 05, 2011 5:49 pm

dipetersen wrote:x=(a+b+c)/ab solve for a

I say it can't be solved. Am I wrong?

Sorry, but yes. This can be solved; it just requires a "trick". You can learn about that trick in this lesson. (Scroll down about two-thirds of the way, to the example showing "Solve Q = 3a + 5ac for a". You'll need to cross-multiply in your equation first, to get rid of the denominator.) :wink:

dipetersen
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Re: Literal equations that can't be solved?

Postby dipetersen » Wed Oct 05, 2011 8:50 pm

I looked at that and maybe I'm missing a step.

By cross-multiply, I assume that you mean

x= (a+b+c)/ab
xab = a+b+c

Then if I subtract b & c from both sides I get

xab - b - c = a

My problem is that I do not know how to get the a out of the xab.

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stapel_eliz
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Postby stapel_eliz » Wed Oct 05, 2011 11:08 pm

dipetersen wrote:xab - b - c = a

My problem is that I do not know how to get the a out of the xab.

Now do like the example showed: Get the terms containing the target variable together on one side, factor, and divide. :wink:

dipetersen
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Re: Literal equations that can't be solved?

Postby dipetersen » Wed Oct 05, 2011 11:26 pm

So if I understand that correctly, it would look something like:

-(b+c)/(1-xb) = a

Right? Thanks for the hints,BTW.

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Postby stapel_eliz » Thu Oct 06, 2011 11:16 am

dipetersen wrote:So if I understand that correctly, it would look something like:

-(b+c)/(1-xb) = a

Yep! :wink:

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Re: Literal equations that can't be solved?

Postby dipetersen » Thu Oct 06, 2011 12:37 pm

Awesome! Thanks for the help.


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