I have never studied the cubic function before so it would be great if someone could explain it to me so that I can answer #25.

Thanks in advance!

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- Aug 30th 2009, 05:01 PMs3aCubic function
I have never studied the cubic function before so it would be great if someone could explain it to me so that I can answer #25.

Thanks in advance! - Aug 30th 2009, 06:34 PMskeeter
- Aug 30th 2009, 06:58 PMDeMath
MS Excel shown

http://i045.radikal.ru/0908/6f/0623997ccc00.png

So we have a equation of population

then in 1925 year the population is - Aug 30th 2009, 07:08 PMRandom Variable
let where is the population in year

then

and so on

What you have is an overdetermined linear system that can be "solved" for the coefficients A, B, C, and D by the method of least squares (which can be done by a program like Maple or Mathematica). - Aug 30th 2009, 07:48 PMDeMath
- Aug 30th 2009, 07:58 PMRandom Variable
I would set up the system in matrix form and use the normal equation.

But it would probably be best to first factorize matrix A using QR decomposition.