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I have a third order polynomial, for example y(x) = -60000x^3 - 260x^2 + 780x + 0.6

I need to know what is x at y = 28 and/or y= 32.

I can goto matlab and find the roots ( x = - .1158, -.0007, and .1122 )

or I can go to

http://www.wolframalpha.com

and it also finds the roots and even plots it for me.

I know I will have three possible x values for any y value, and given the xrange (which I will know) that might be ok, I can select which one to use, buthow do I go from the roots of that poly to knowing how to solve for x when Y is a real number ?

any help, suggestions, anything ...is very much appreciated.

Thanks

Dubs

( btw - I do realize there is a thread on here that addresses this subject from 2013 but I do not understand it so linking me to it doesn't help me at this time )

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# I Need help solving for X in third order polynomial

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