Question

What is the second derivative of `f(x)=cos(-x)-sinx`?

Answer 1

`f''(x) = -cosx + sinx`

Explanation:

The function can be simplified as

`f(x) = cosx - sinx`

Differentiating once:

`f'(x) = -sinx - cosx`

Differentiating again:

`f''(x) = -cosx + sinx`