Answer
$x \lt -\frac{1}{3}~~~$ or $~~~x \geq 1$
The solution set is $~~~(-\infty, -\frac{1}{3}) \cup [1, \infty)$
Work Step by Step
$-3 \lt \frac{1}{x} \leq 1$
Case 1: $x \lt 0$
$-3 \lt \frac{1}{x}$
$-\frac{1}{3} \gt x$
Case 2: $x \gt 0$
$\frac{1}{x} \leq 1$
$x \geq 1$
Solution:
$x \lt -\frac{1}{3}~~~$ or $~~~x \geq 1$
The solution set is $~~~(-\infty, -\frac{1}{3}) \cup [1, \infty)$