actu.125..Has anyone come across a time when their trendline and data do not
match up?

I have to use a 6th order poly fit on some data I've got. The curve fits
the actual data fine, but when I plot out points using the trendline equation
my data goes crazy.

I have this 6th order equation and x data ranging from 0 to 180 in
increments of 5. the last term of the equation is the y intercept (if x is 0
all other terms fall out) but the trendline eq and the actual data aren't
even close here. The trendline says my y intercept should be .0031, whereas
the actual data (that I created the trendline from) has the y int at .125.
My graph is somewhat sinusoidal... not really but you get the idea, but when
I enter the incremental x data from 0 to 180 into the equation the graph
blows up. The max actual data is around 3 on the y axis and 90 on the x, the
max trendline data is 60 at x = 45. The min actual data is at the y inercept
and is .125 when x = 0 the trendline eq says the min is 3.69 million at x =
180... what gives??!?