Select a 6 column x 1 row range and enter the array formula:

=LINEST(B2:B51,A2:A51^{1,2,3,4,5})

Use ctrl+shift+enter to exeute.

e.g. with

x 1 2 3 4 5 6
y 3 5 7 8 9 11

the formula returns the six coefficients in descending order:

y = -0.016666667x^5 + 0.333333333x^4 -2.416666667x^3 +7.666666667x^2
-8.566666667x +6


On 9 Mar, 09:13, Doublee wrote:
How do I calculate the coefficients of a 5th order polynomial? A reference
would suffice. The data consists of up to 50 equally spaced data points and
consists of real positive numbers. I am already aware of the equation as
displayed in Excel on the chart but the format is not useful to me because I
want to embed the calculations of the coefficients into an Excel 2007 cell.