with the usual coefficients:
a in A1
b in B1
c in C1

use:

=(-B1+(B1*B1-4*A1*C1)^0.5)/(2*A1)
=(-B1-(B1*B1-4*A1*C1)^0.5)/(2*A1)


For for A1 thru C1:

10 60 30

the formulas return the Real roots:

-0.550510257
-5.449489743

For non-Real roots you must use more "imaginative" methods.
--
Gary''s Student - gsnu200860


"DataSchemer" wrote:

I know there is a trend line avail. with poly fit and you can change to
numbers.
However when reversing this formula to solve for X there is no help in
excel. Is there an add in or someone whith a spreadsheet that can help?

Simple Quadratic help would do?