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Author: Subject: Mathematical solution to two quadratics
JohnWW
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chemoleo
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Solution?

Ok, I've done some work on this:
With the hint from len1 I did the following:
(I'd appreciate someone checking, I'm utterly paranoid I made a mistake somewhere...pleeeease! )
See attachment.

Substituting this into the cubic solution is ok, but now I have another problem: I need to find some regression software that can handle the third root! I couldn't find such a function in Sigmaplot - is anyone aware of graphing software that does advanced regression offering a third root function?

Please be aware that I fit real data (as Fobs) as in

Fobs = Fmin(Lo-[PL]) + Fmax([PL])

where Fobs are about 50 data points.
I therefore have to plug in the cubic solution into each [PL] in the eqn above, and by varying the KdPL (substituted as a) I get the best fitting curve (and the KdPL therefore is value I'm after)... Not sure if this is all making sense, but I did explain it in one of the attachments above.

Anyway, I'm now stuck with trying to find regression software that offers the third root... anyone?

Thanks!

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 Sciencemadness Discussion Board » Fundamentals » Miscellaneous » Mathematical solution to two quadratics Select A Forum Fundamentals   » Chemistry in General   » Organic Chemistry   » Reagents and Apparatus Acquisition   » Beginnings   » Responsible Practices   » Miscellaneous   » The Wiki Special topics   » Technochemistry   » Energetic Materials   » Biochemistry   » Radiochemistry   » Computational Models and Techniques   » Prepublication Non-chemistry   » Forum Matters   » Legal and Societal Issues