Answer
Done below.
Work Step by Step
a) If $x^3 \geq 1$, then $x$ can't be negative or 0. So the truth set is $\{1, 2, \cdots\}$.
b) If $x^2 = 2$, then $x = \pm \sqrt{2}$ and $x$ can't be an integer. Thus the truth set is empty.
c) If $x < x^2$, then $x - x^2 < 0$ so that $x(1 - x) < 0$. This will happen for any integer $x$ that isn't 0 or 1.
