Tính tích phân của: \[I = \int {(2x + 1){e^{3x}}dx} \]

\[I = \frac{1}{3}(2x + 1){e^{3x}} - \frac{1}{9}{e^{3x}} + C\]

\[I = \frac{1}{6}(2x + 1){e^{3x}} - \frac{1}{3}{e^{3x}} + C\]

\[I = \frac{1}{2}(2x + 1){e^{3x}} - \frac{1}{9}{e^{3x}} + C\]

\[I = \frac{1}{6}(2x + 1){e^{3x}} - \frac{1}{9}{e^{3x}} + C\]