How to transform many variables and make a regression model for each of them in R

Question

Here data example

mydat=structure(list(x1 = c(0, 0, 0, 0.5, 0.5, 0.5, 0, 0, 0, 0, 0), 
    x2 = c(0, 0, 0, 0.5, 0.5, 0.5, 0, 0, 0, 0, 0), x3 = c(25.5, 
    25.5,