Answer:
4 (2a+3b)^2
Step-by-step explanation:
(4a+6b)^2 = (4a+6b) * (4a+6b) = 16a^2 +48ab + 36b^2
take 4 common factor
4 (4a^2 + 12ab + 9b^2) = 4 (2a+3b)^2