To enter prime notation in Math-2D I currently do

k^2 + `k'`^2 = 1;
                           2     2    
                          k  + k'  = 1

To enter a back tick (left single quote symbol) this requires with my keyboard shift+(key for `) followed by hitting the space bar.

The output looks nice

However to enter k' in a new input line, dragging and dropping k' (which normally works for other expressions) from a former output does not work. The result is

Instead of changing default typesetting rules, I made k' atomic and dragged it to the favourite palette. This is an acceptable solution to avoid keyboard acrobatics. The only drawback is that the favourite palette gets crowded after a while.

I was wondering whether there are other ways to enter prime notation in a less complicated way as I have described above?

Has anybody seen the unit palette beeing empty? 

This is new to me. I normally use the unit entry in the favourites but this time wanted to try Maple presets.

I am looking for a command that extracts sqrt(2) from

sqrt(4 + (-2*x - 2)*y)

The expression above is a subexpression of a larger expression generated by Maple (an integral).
In this situation manual workarounds are impractical and errorprone.

Ideally Maple should return

sqrt(2)*sqrt(2 - (x + 1)*y)

I tried simplify, factor, collect and so on...

In case that there is nothing (which I doubt):
Why is Maple not having simple commands that do extraction (and absortion/inclusion) of factors?

(extract and absorb are names not used so far that would be easy to remember.)  

Update - example of an expression:

expr := Int(sqrt(-2*alpha^2*x - 2*alpha^2 + 4)/(sqrt(-alpha^2 + 1)*(-alpha^2*x - alpha^2 + 2)), alpha = 0 .. z) = EllipticF(z, sqrt(2*x + 2)/2)

When clicking on a pink error message I get this

Can someone explain what is going on? Quite unusual for me all this.

I do not have a server to white list. What can I do about it?

Is that Sucuri thing safe?

By symbolic regression I mean an algorithm that determines a model (fit function) that fits best to a data set.

Are there any commands, packages, libraries or MaplesPrime post that are helpful in this regrad?

Edit: For the data set below a symbolic regression could ideally algortihm return "simple" models (formulas)  that use a "minimal" number of terms.

Download regression_dataset.mw