Answer:
[tex]27a^{3} +27a^{2}b+9ab+b^{3}[/tex]
Step-by-step explanation:
[tex](3a+b)(3a+b) = 9a^{2}+6ab+b^{2}\\(9a^{2}+6ab+b^{2})(3a+b) = 27a^{3} + 27a^{2}b +9ab^{2} +b^{3}[/tex]
9a^3+18a^2b+9ab^2+b^2
