Finding multiple trendlines

I have a large dataset of x and y variables. I need to find the trendline (specifically slope (or Beta)) for many groups of data. For example:
1st I need trendline for -> x1:x100 and y1:y100
then I need one for x2:x101 and y2:y101
and so on x3:x102 and y3:y102

I think the LINEST and LOGEST functions may help but I'm unsure how to use them.

I hope this makes since, if not, it is basically a rolling regression and I need to find all Betas for each group of 100 observations.

Thanks in advance,
Joe

Beta is just the slope, right?

With the independent variable in column A, and the dependent variable in column B, in C1 and copy down,

=LINEST(B1:B100, A1:A100)

Yes, the answer was right in my question, that worked for me!
Thanks