Find \(\int \left( x ^ { 3 } - 2 x \right) \mathrm { d } x\).
The graph below shows part of the curve \(y = x ^ { 3 } - 2 x\) for \(0 \leq x \leq 2\).
\includegraphics[max width=\textwidth, alt={}, center]{c55a5f04-3573-4f36-a12c-3755bdd4a45b-2_528_1019_520_321}
Show that the area of the shaded region \(P\) is the same as the area of the shaded region \(Q\).