How do I solve for x in a second-order polynomial trend?

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DianeD

I have instrument calibration data that is best characterized as quadratic- I
need to back-calculate for an adjusted point, using the basic formula y= ax^2
+ bx + c.

I'm horrible at formulae in excel!
 
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David Biddulph

You could use Goal Seek to find X, given Y, or you could use the standard
quadratic equation solution (-B +/- SQRT(B^2-4*A*C))/(2*A)
 
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