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June 17th, 2012, 12:20 AM   #1
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Simplifying equation

Hi friends,

I have a following equation :

x = x2 - [(N-1) * 2], where N = 11

that becomes:

x = x2 - (20)

My question:
If possible, how can we derive the value of x in the equation x = x2 - (20) ?

Thanks in advance,
Regards.
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June 17th, 2012, 03:00 AM   #2
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Re: Simplifying equation

Quote:
Originally Posted by bytelogik
x = x2 - [(N-1) * 2], where N = 11
that becomes:
x = x2 - (20)
My question:
If possible, how can we derive the value of x in the equation x = x2 - (20) ?
I assume x2 means x squared or x to the power 2: next time, show like this: x^2 (^ is power sign).

x = x^2 - 20
Rearrange:
x^2 - x - 20 = 0
Factor:
(x - 5)(x + 4) = 0

So x = 5 or x = -4

Any reason you were having trouble with that? Quite basic...
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June 17th, 2012, 03:15 AM   #3
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Re: Simplifying equation

Denis, thanks for your reply.
But how do you figure out 5 and 4 ? What if the number 20 in the example equation is really a large value of which we do not know the products.
Someone suggested for using quadratic formula for such equations.

"Any reason you were having trouble with that? Quite basic..."
Mathematics is a beautiful but complex arena and I am not even an average math expert. But I often try to solve really complex problems like 3D progression space for which I always want direct and simple equations. Studying progression sequences is just an part of it. I think learning and implementing maths to odd problems helps me to relax for a while and makes my logical strength more sharper.
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June 17th, 2012, 06:01 PM   #4
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x = x - 20 is equivalent to (x - 1/2) = 20 + 1/4, so you can find x - 1/2 and hence x.
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