Kobe C. answered 06/24/20
AP Calculus and AP Music Theory Tutor
So generally, when you're trying to find the area under the curve, you want to integrate the function within the bounds in question, which in this case is 3 and 5. As a result, you get 4e^x - x^2/2. Then you want to subtract this when you put 3 in for x from when you put 5 in for x, such as the following:
(4e^5-25/2) - (4e^3 - 9/2)
When you combine like terms, you end up with the following answer:
4e^5 - 4e^3 - 8 square units
However, you can approximate the answer to 505.31 square units.