Completely factor the following expression:

4a2 – 12ab + 9b2

Solution:

4a2 - 12ab + 9b2

= (2a)^2 -2*2a*3b + (3b)^2

= (2a-3b)(2a-3b)

= (2a-3b)^2

So the result is (2a-3b)^2