Answer: e3x/3 + C.
- A 3e3x + C
- B e3x/3 + C
- C e3x + C
- D 3x e3x + C
Correct answer: B. e3x/3 + C
Explanation: Integral of eax = eax/a + C. Here a=3: e3x/3 + C.
The exact area under the curve from a to b (shaded) is approximated by a few rectangles, the Riemann sum idea behind the definite integral.