Answer:
9a^2 -12ab +4b^2
Explanation:
Using the distributive property, you multiply 3a and 3a, which gives you 9a^2. Then you multiply 3a and -2b, which gives you -6ab. Then you multiply -2b and 3a, which gives you -6ab. And finally, you multiply -2b and -2b, which gives you +4b^2. 9a^2 -6ab -6ab +4b^2. Combine like terms (-6ab and -6ab). Then you have 9a^2 -12ab +4b^2