I am attempting to extract polonomial factors for a data set. At 6th order,
the process falls apart.
My data is
X=0,100,200,300,400,500,600,700,800,900,100
Y=0,0.1,-3.1,-12,-29.5,59.2,-106.4,177.6,280.2,421.3,606.2

At 6th order the C6,b and R-aquared values are crazy.

My formula a
C6=INDEX(LINEST(y,x^{1,2,3,4,5,6}),1)
b=INDEX(LINEST(y,x^{1,2,3,4,5,6}),1,7)
R-squared=INDEX(LINEST(y,x^{1,2,3,4,5,6},TRUE,TRUE), 3)

Any suggestions?

In addition to this, I would like to determine if using these functions, can
the trendline factor calculation be forced thru the origin 0,0?