Let $x \in \mathbb{R}$ be a D993: Real number.
Then
| (1) | \begin{equation} |x| < 1 \quad \implies \quad \sum_{n = 0}^{\infty} x^n = \frac{1}{1 - x} \end{equation} |
| (2) | \begin{equation} x \geq 1 \quad \implies \quad \sum_{n = 0}^{\infty} x^n = \infty \end{equation} |
| (3) | \begin{equation} x \leq -1 \quad \implies \quad \sum_{n = 0}^{\infty} x^n = \emptyset \end{equation} |