Determine where the given function is increasing and where it is decreasing
\[
f(x)=2 x^{3}+15 x^{2}+24 x
\]
(i) Decreasing on \( (-\infty,-2) \) and \( (-1, \infty) \), increasing on \( (-2,-1) \)
(ii) Increasing on \( (-\infty,-4] \) and \( [-1, \infty) \), decreasing on \( [-4,-1] \)
(iii) Increasing on \( (-\infty,-2) \) and \( (-1, \infty) \), decreasing on \( (-2,-1) \)
(iv) Decreasing on \( (-\infty,-4) \) and \( (-1, \infty) \), increasing on \( (-4,-1) \)
