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Topic: Re: Very tough math equation.Riddle Only experts c (Read 1146 times) |
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Whiskey Tango Foxtrot
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Re: Very tough math equation.Riddle Only experts c
« on: Dec 8th, 2006, 1:18pm » |
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This seems easy so I'll just give a hint.
| hidden: | Start with C = B2 - 4AC
Then,
C + 4AC = B2
C (1 + 4A) = B2
C = B2/(1 + 4A) |
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ThudnBlunder
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Re: Very tough math equation.Riddle Only experts c
« Reply #1 on: Dec 8th, 2006, 1:53pm » |
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on Dec 8th, 2006, 1:22pm, koonie32 wrote:But a and B are the ROOTS of that equation. Which makes no sense to me..
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You should know the formula for the SUM of the roots.
You should know the formula for the PRODUCT of the roots.
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SMQ
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Re: Very tough math equation.Riddle Only experts c
« Reply #2 on: Dec 8th, 2006, 1:56pm » |
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They're both the roots and the coefficients, if I understand the problem statement correctly. WTF can correct me if I'm wrong, but I believe it's fairly simple to show using the above derivation of C and the equation B = (-B +/- [sqrt]C)/2A that the only solution is the trivial one.
--SMQ
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ThudnBlunder
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Re: Very tough math equation.Riddle Only experts c
« Reply #3 on: Dec 8th, 2006, 2:47pm » |
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on Dec 8th, 2006, 2:30pm, koonie32 wrote:Can someone just go by a step by step thing
A and B are equal to the roots of AX^2 + bx + c.
They are the same variables |
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For the equation Ax2 + Bx + C = 0
sum of roots = A + B = -B/A (text-book formula)....equation 1
product of roots = AB = C/A (text-book formula)....equation 2
And WTF gave you the third equation.
So there are 3 equations to solve in 3 unknowns.
By the way, x is the only variable in the quadratic equation Ax2 + Bx + C = 0
A,B,C are constants whose values you must find using the info supplied.
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| « Last Edit: Dec 8th, 2006, 3:02pm by ThudnBlunder » |
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Whiskey Tango Foxtrot
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Re: Very tough math equation.Riddle Only experts c
« Reply #4 on: Dec 8th, 2006, 3:02pm » |
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You're correct, SMQ. koonie should have this whipped by now. 
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ThudnBlunder
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Re: Very tough math equation.Riddle Only experts c
« Reply #5 on: Dec 8th, 2006, 3:18pm » |
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Quote: When you say "sum of roots" normally this would mean x. Correct?
But in this case the sum of roots can be A + B
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Well, as A,B are the roots Ax2 + Bx + C = 0 when x = A and when x = B
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| « Last Edit: Dec 8th, 2006, 3:23pm by ThudnBlunder » |
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Icarus
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Re: Very tough math equation.Riddle Only experts c
« Reply #6 on: Dec 8th, 2006, 3:50pm » |
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Did somebody delete the original post for some reason?
As for the Lemmings problem, "kookie" posted a new thread for it yesterday in the Medium forum, and you can find the answer there. If you don't get the hints, Miles pretty much spells out why it is that the lemmings bumping into each other and changing direction doesn't make any difference.
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Icarus
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Re: Very tough math equation.Riddle Only experts c
« Reply #7 on: Dec 8th, 2006, 3:58pm » |
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Nope. Deleting topics is reserved for William, towr, and myself, and we prefer not to do so without strong reason. Everyone else can affect only their own posts.
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"Pi goes on and on and on ...
And e is just as cursed.
I wonder: Which is larger
When their digits are reversed? " - Anonymous
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