The trend line equations displayed in Excel normally do not have sufficient
significant places to be used directly in an equation.
Select the trend line equation on the chart and change the format such that
there are more significant places.
(This has burnt me in the past, I always check by plotting the calculated
values on the chart with the trend line showing to insure I amm close enough.)

"Ismael Jr" wrote:

Hi.
I drew a graph using some data. So I asked Excel to put the tendency curve
using a 5th degree polinomial. I also asked for the equation. The problem is
when I input the points into the equation the y values do not correspond to
the ones in the graph.
Can you help me? If necessary I can send you the file with the data.
Thanks.