Question

How do you factor by grouping `4z^2+12z-az-3a`?

Answer 1

(4z-a)(z+3)

Make groups as (4`z^2` +12z) - (az+3a). Now take out common factors from both groups as follows:
4z(z+3) -a(z+3).Since z+3 is common to both the terms now, we can again take out the common factor to become (z+3)(4z-a).