Consider the function f(x)=3cosx−cos3x for 0<x<2π

Question

1. f(x) is concave up on the interval(s)=_____
2. f(x) is concave down on the interval(s)=_____

Answer 1

Concave up on 0 to π/4, 3π/4 to π, 5π/4 to 7π/4

Concave down on π/4 to 3π/4, π to 5π/4, 7π/4 to 2π