Calculating next point from slope data

[marq1]

Ive got a set of data points (4.5,3.8.3.5,& 2.3) that generates a Trend line. I want to use that slope to calculate the next (5th) point.

What is the formula needed to do this? I assume it's just the slope value but I'm not sure how to write this.

 

[VoG]

This might help http://www.mrexcel.com/forum/showthread.php?t=530402