Q: Consider any three-variable linear regression model:
Yt = α1 + α2X2t + α3X3t + u1t
Suppose you multiply all the X2 values by 2. What will be the effect of
this rescaling, if any, on the estimates of the parameters and their standard
errors?

Doubt: Will intercept and slope cofficients remain unaffected or get divided by 1/2 or any other answer?

These equation also show, slope coefficient of x2 become half, when X2 multiply by 2 then the Numerator of a2 will double and denominator become 4 time.

Guys, I don't know whether its available online or not,,
these are from tuition pdf notes, from where pdf is not able to be extracted even, otherwise even i would have posted obviously.

yes, u may post as many ques. u want from the book back ques. to ask on the forum here, i will post screenshots of all those( as i did in above case)