∫(3x+1)3dx=....\int\left(3x+1\right)^3dx=....∫(3x+1)3dx=....
112(3x+1)4+C\frac{1}{12}\left(3x+1\right)^4+C121(3x+1)4+C
14(3x+1)4+C\frac{1}{4}\left(3x+1\right)^4+C41(3x+1)4+C
112(3x+1)12+C\frac{1}{12}\left(3x+1\right)^{12}+C121(3x+1)12+C
13(3x+1)4+C\frac{1}{3}\left(3x+1\right)^4+C31(3x+1)4+C
(3x+1)4+C\left(3x+1\right)^4+C(3x+1)4+C