`int e^(3x) dx `

`==gt u= 3x ==gt du = 3 dx `

`==gt int e^(3x) dx = int e^u (du)/3 `

`==gt int e^(3x) dx = (1/3) int e^u du = (1/3) e^u + C `

`==gt int e^(3x) dx = (1/3) e^(3x) + C`

``

`int e^(3x) dx `

`==gt u= 3x ==gt du = 3 dx `

`==gt int e^(3x) dx = int e^u (du)/3 `

`==gt int e^(3x) dx = (1/3) int e^u du = (1/3) e^u + C `

`==gt int e^(3x) dx = (1/3) e^(3x) + C`

``