posted by Nicola .
Consider the function f(x)=3cosx−cos^(3)x for 0<x<2π.
For the following questions, write inf for ∞, -inf for −∞, U for the union symbol, None if no answer exists, and separate by a comma if more than one answer exist.
a.) The x-intercepts are .
b.) f′(x)= .
c.) f(x) is increasing on the interval(s) .
d.) f(x) is decreasing on the interval(s) .
e.) f(x) has a local maximum at x = .
f.) f(x) has a local minimum at x = .
g.) f′′(x)= .
h.) f(x) is concave up on the interval(s) .
i.) f(x) is concave down on the interval(s) .
j.) The x-coordinate of the points of inflection are