SOLUTION: I have a polynomial regression and I am trying to build a calculation to solve for x. The equation I am looking at is x^2+x+b=y. I can calculate the y easy enough, but writing an e

Algebra ->  Exponential-and-logarithmic-functions -> SOLUTION: I have a polynomial regression and I am trying to build a calculation to solve for x. The equation I am looking at is x^2+x+b=y. I can calculate the y easy enough, but writing an e      Log On


   

Question 550851: I have a polynomial regression and I am trying to build a calculation to solve for x. The equation I am looking at is x^2+x+b=y. I can calculate the y easy enough, but writing an excel formula to determine X has got me beat.
thanks
Answer by scott8148(6628) About Me  (Show Source):
You can put this solution on YOUR website!
this is an application of the quadratic formula

x^2 + x + (b - y) = 0

x = {-1 ± [sqrt(1 - 4(b - y))]} / 2

the ± may generate two values for x; you probably want two equations, one + and one -