To factorize the expression
, you can first look for common factors in pairs of terms. In this case, you can factor by grouping:

Now, let's factor each of these groups separately:
For the first group,
you can factor it as follows:

For the second group,
, you can factor out the common factor of 3z:

Now, you have factored in both groups:

So, the fully factorized expression is
