Answer
Done below.
Work Step by Step
a) There exists a real number $x$ such that $x^3 = -1$. This is true (take $x = -1$).
b) There exists an integer $x$ such that $x + 1 > x$. This is true, for any integer.
c) For all integers $x$, $x - 1$ is an integer. This is true.
d) For all integers $x$, $x^2$ is an integer. This is true.
