The expression 4abx - 2axy -12bx + 6bxy can be factorized completely as follows:

First, we can group the first two terms and the last two terms:

(4abx - 2axy) + (-12bx + 6bxy)

Then, we can factor out the greatest common factor from each group:

2ax(2b - y) - 6bx(2 - y)

Now, we can factor out the greatest common factor from the entire expression:

2x(2b - y)(a - 3b)

So, the completely factorized form of the expression is 2x(2b - y)(a - 3b)