Automatic formula updating

Hi. I have a sheet of data, where the very first row are x-values, and all the remaining rows (below those x-values) are the y-values. this is based on an experiment, and for every x-value there are lots of y-values. I want to calculate a trendline for each experiment, which obviously uses the same x-values.

I used the 'slope' function, which works fine, but then when I drag down that formula into each of the different rows (to calculate the regression for each experiment), it automatically increments the "known X's) down one...which I don't want since all the regressions will have the same x-values. here is a sample of my sheet, since it's easier to visualize than the above description:

x1 x2 x3 x4 x5
y11 y12 y13 y14 y15
y21 y22 y23 y24 y25
y31 y32 y33 y34 y35
...

Again, that first row of x-values goes along with ALL the y-value lines. is there a way to make that first row (the x-values) a constant, which I can pass to the 'slope' formula, so that it doesn't update?

Thanks, and I hope this made sense.

Welcome to the forum.

See Help About cell and range references