Linear Regression

[tiredofit]

I have two data points in my data, a and b and I am trying to forecast point c.

Assuming a linear relationship, surely point c would be:

(b-a) + a

However if I use Excel's linear forecast function in the graph, I get an equation that does not give me the same figure.

In my data, a = 32,325,734, b = 35,966,563, so by my calculations, c would be 39,607,393.

The equation of best fit in Excel gives:

y = 4E+06x + 3E+07

with R^2=1 (correct)

so according to the equation, c = 42,000,000

What is the problem?

Thanks

 

[tiredofit]

Sorted: I increased the accuracy of the equation:

Should be:

y = 3,640,829x + 28,684,904