Here is the origional Formula
w=a*x^3+b*x^2+c*x+d
I need to re-arange the formula so that I can input a "x" to get the "w".
This is a calibration curve for a basis weight sensor the x is a voltage ratio and the w is weight in grams per square meter.
Thanks
2006-11-07 06:19:00 · 4 answers · asked by A W 2 in Science & Mathematics ➔ Mathematics
OOPS I mean I want to put in a W and get an x value.
2006-11-07 06:44:32 · update #1
Can I answer my own question I guess I did. Its not all that bad. but mr mathman was right it is nasty but Im going to plug it into a spread sheet hope it works.
http://www.math.vanderbilt.edu/~schectex/courses/cubic/
2006-11-07 06:56:55 · update #2
This *is* the way to write it so that x is the input and w is the output. If you want to solve for x in terms of w (i.e. have w the input and x the output), you are better off doing numerical approximations than using the cubic formula (it is really, really nasty).
2006-11-07 06:22:18 · answer #1 · answered by mathematician 7 · 1⤊ 1⤋
It's already set up to give you the answer for w, assuming of course you have a,b,c,d and x.
The formula you gave, w=a*x^3+b*x^2+c*x+d, is the general form of a order 3 polynomial.
2006-11-07 06:22:46 · answer #2 · answered by poorcocoboiboi 6 · 0⤊ 1⤋
Look up Cardano's method:
2006-11-07 06:55:20 · answer #3 · answered by Anonymous · 0⤊ 0⤋
You don't have to do anything.
2006-11-07 06:24:41 · answer #4 · answered by ag_iitkgp 7 · 0⤊ 1⤋