One line PredY ? Statistics 2Var

[Schraf]

Hello.

No problem finding the value of y using the method below:

C1:={750,850} --> x1 and x2
C2:={55,65} --> y1 and y2

Predict y3 knowing x3=813.7 :

PredY(813.7) --> 61.37 (linear regression)

It's also ok when I use the data columns in Statistics 2Var App.

But in the documentation we can read: PredY(mode, x, parameters)

mode = 1 for linear regression (OK ?)
x = 813.7 (OK ?)
parameters ?? I try {{750,850},{55,65}} or the slope and Y-intercept but it does not work.

Do you have an idea ?