Final answer:
To determine the intervals on which f is concave up and concave down, find the second derivative of f(x). Set the second derivative greater than zero to find the intervals where f is concave up. Set it less than zero to find the intervals where f is concave down.
Step-by-step explanation:
To determine the intervals on which f is concave up and concave down, we need to find the second derivative of f(x). The second derivative of f(x) is given by: f''(x) = -3sin(x) - 5cos(x).
To find the intervals where f is concave up, we need to find where f''(x) > 0. Set f''(x) > 0 and solve for x:
-3sin(x) - 5cos(x) > 0
Solving this inequality will give us the intervals where f is concave up. Similarly, to find the intervals where f is concave down, we need to find where f''(x) < 0.