It is 'wrong' because the value of y=ax^4+bx^3+cx^2+dx+e if very sensitive
to the values of the confinements (a, b,....)
You could format the trendline and get more precision and then very
carefully copy the values OR you could you LINEST as shown at
http://people.stfx.ca/bliengme/ExcelTips/Polynomial.htm
best wishes
--
Bernard V Liengme
www.stfx.ca/people/bliengme
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"jkeith" wrote in message
...
fitting a trendline to data and the polynomial equation it spits out is
obviously wrong. Any ideas? thanks