Question

Find all relative extrema. Use the Second Derivative Test where applicable.
f(x) = 2sin + cos 2x , [0;2pi]

Answer 1

Do you know the first derivative of f(x)?

Answer 2

Oops, I think I got it, thanks :D @Valpey

Answer 3

We are using the second derivative test because all relative extrema will have f''(x) = 0.

One special consideration, though is to keep in mind that points where f''(x) = 0 will not necessarily be relative extrema.